Add Anthropic API integration, remove locale settings UI

Anthropic API:
- Add @anthropic-ai/sdk with adapter wrapping OpenAI-shaped interface
- Support Claude models (opus, sonnet, haiku) with extended thinking
- Auto-reset model on provider switch, JSON retry logic
- Add Claude model pricing to ai-usage tracker
- Update AI settings form with Anthropic provider option
- Add provider field to AIUsageLog for cross-provider cost tracking

Locale Settings Removal:
- Strip Localization tab from admin settings (mobile + desktop)
- Remove i18n settings from router and feature flags
- Remove LOCALIZATION from SettingCategory enum
- Keep franc document language detection intact

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/settings/ai-settings-form.tsx

@@ -1,5 +1,6 @@
 'use client'
 
+import { useEffect, useRef } from 'react'
 import { useForm } from 'react-hook-form'
 import { zodResolver } from '@hookform/resolvers/zod'
 import { z } from 'zod'
@@ -36,6 +37,7 @@ const formSchema = z.object({
   ai_model: z.string(),
   ai_send_descriptions: z.boolean(),
   openai_api_key: z.string().optional(),
+  anthropic_api_key: z.string().optional(),
   openai_base_url: z.string().optional(),
 })
 
@@ -48,6 +50,7 @@ interface AISettingsFormProps {
     ai_model?: string
     ai_send_descriptions?: string
     openai_api_key?: string
+    anthropic_api_key?: string
     openai_base_url?: string
   }
 }
@@ -63,12 +66,29 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
       ai_model: settings.ai_model || 'gpt-4o',
       ai_send_descriptions: settings.ai_send_descriptions === 'true',
       openai_api_key: '',
+      anthropic_api_key: '',
       openai_base_url: settings.openai_base_url || '',
     },
   })
 
   const watchProvider = form.watch('ai_provider')
   const isLiteLLM = watchProvider === 'litellm'
+  const isAnthropic = watchProvider === 'anthropic'
+  const prevProviderRef = useRef(settings.ai_provider || 'openai')
+
+  // Auto-reset model when provider changes
+  useEffect(() => {
+    if (watchProvider !== prevProviderRef.current) {
+      prevProviderRef.current = watchProvider
+      if (watchProvider === 'anthropic') {
+        form.setValue('ai_model', 'claude-sonnet-4-5-20250514')
+      } else if (watchProvider === 'openai') {
+        form.setValue('ai_model', 'gpt-4o')
+      } else if (watchProvider === 'litellm') {
+        form.setValue('ai_model', '')
+      }
+    }
+  }, [watchProvider, form])
 
   // Fetch available models from OpenAI API (skip for LiteLLM — no models.list support)
   const {
@@ -119,6 +139,9 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
     if (data.openai_api_key && data.openai_api_key.trim()) {
       settingsToUpdate.push({ key: 'openai_api_key', value: data.openai_api_key })
     }
+    if (data.anthropic_api_key && data.anthropic_api_key.trim()) {
+      settingsToUpdate.push({ key: 'anthropic_api_key', value: data.anthropic_api_key })
+    }
 
     // Save base URL (empty string clears it)
     settingsToUpdate.push({ key: 'openai_base_url', value: data.openai_base_url?.trim() || '' })
@@ -139,6 +162,9 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
   )
 
   const categoryLabels: Record<string, string> = {
+    'claude-4.5': 'Claude 4.5 Series (Latest)',
+    'claude-4': 'Claude 4 Series',
+    'claude-3.5': 'Claude 3.5 Series',
     'gpt-5+': 'GPT-5+ Series (Latest)',
     'gpt-4o': 'GPT-4o Series',
     'gpt-4': 'GPT-4 Series',
@@ -147,7 +173,7 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
     other: 'Other Models',
   }
 
-  const categoryOrder = ['gpt-5+', 'gpt-4o', 'gpt-4', 'gpt-3.5', 'reasoning', 'other']
+  const categoryOrder = ['claude-4.5', 'claude-4', 'claude-3.5', 'gpt-5+', 'gpt-4o', 'gpt-4', 'gpt-3.5', 'reasoning', 'other']
 
   return (
     <Form {...form}>
@@ -187,13 +213,16 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
                 </FormControl>
                 <SelectContent>
                   <SelectItem value="openai">OpenAI (API Key)</SelectItem>
+                  <SelectItem value="anthropic">Anthropic (Claude API)</SelectItem>
                   <SelectItem value="litellm">LiteLLM Proxy (ChatGPT Subscription)</SelectItem>
                 </SelectContent>
               </Select>
               <FormDescription>
                 {field.value === 'litellm'
                   ? 'Route AI calls through a LiteLLM proxy connected to your ChatGPT Plus/Pro subscription'
-                  : 'Direct OpenAI API access using your API key'}
+                  : field.value === 'anthropic'
+                    ? 'Direct Anthropic API access using Claude models'
+                    : 'Direct OpenAI API access using your API key'}
               </FormDescription>
               <FormMessage />
             </FormItem>
@@ -211,37 +240,71 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
           </Alert>
         )}
 
-        <FormField
-          control={form.control}
-          name="openai_api_key"
-          render={({ field }) => (
-            <FormItem>
-              <FormLabel>{isLiteLLM ? 'API Key (Optional)' : 'API Key'}</FormLabel>
-              <FormControl>
-                <Input
-                  type="password"
-                  placeholder={isLiteLLM
-                    ? 'Optional — leave blank for default'
-                    : (settings.openai_api_key ? '••••••••' : 'Enter API key')}
-                  {...field}
-                />
-              </FormControl>
-              <FormDescription>
-                {isLiteLLM
-                  ? 'LiteLLM proxy usually does not require an API key. Leave blank to use default.'
-                  : 'Your OpenAI API key. Leave blank to keep the existing key.'}
-              </FormDescription>
-              <FormMessage />
-            </FormItem>
-          )}
-        />
+        {isAnthropic && (
+          <Alert>
+            <Info className="h-4 w-4" />
+            <AlertDescription>
+              <strong>Anthropic Claude Mode</strong> — AI calls use the Anthropic Messages API.
+              Claude Opus models include extended thinking for deeper analysis.
+              JSON responses are validated with automatic retry.
+            </AlertDescription>
+          </Alert>
+        )}
+
+        {isAnthropic ? (
+          <FormField
+            control={form.control}
+            name="anthropic_api_key"
+            render={({ field }) => (
+              <FormItem>
+                <FormLabel>Anthropic API Key</FormLabel>
+                <FormControl>
+                  <Input
+                    type="password"
+                    placeholder={settings.anthropic_api_key ? '••••••••' : 'Enter Anthropic API key'}
+                    {...field}
+                  />
+                </FormControl>
+                <FormDescription>
+                  Your Anthropic API key. Leave blank to keep the existing key.
+                </FormDescription>
+                <FormMessage />
+              </FormItem>
+            )}
+          />
+        ) : (
+          <FormField
+            control={form.control}
+            name="openai_api_key"
+            render={({ field }) => (
+              <FormItem>
+                <FormLabel>{isLiteLLM ? 'API Key (Optional)' : 'OpenAI API Key'}</FormLabel>
+                <FormControl>
+                  <Input
+                    type="password"
+                    placeholder={isLiteLLM
+                      ? 'Optional — leave blank for default'
+                      : (settings.openai_api_key ? '••••••••' : 'Enter API key')}
+                    {...field}
+                  />
+                </FormControl>
+                <FormDescription>
+                  {isLiteLLM
+                    ? 'LiteLLM proxy usually does not require an API key. Leave blank to use default.'
+                    : 'Your OpenAI API key. Leave blank to keep the existing key.'}
+                </FormDescription>
+                <FormMessage />
+              </FormItem>
+            )}
+          />
+        )}
 
         <FormField
           control={form.control}
           name="openai_base_url"
           render={({ field }) => (
             <FormItem>
-              <FormLabel>{isLiteLLM ? 'LiteLLM Proxy URL' : 'API Base URL (Optional)'}</FormLabel>
+              <FormLabel>{isLiteLLM ? 'LiteLLM Proxy URL' : isAnthropic ? 'Anthropic Base URL (Optional)' : 'API Base URL (Optional)'}</FormLabel>
               <FormControl>
                 <Input
                   placeholder={isLiteLLM ? 'http://localhost:4000' : 'https://api.openai.com/v1'}
@@ -255,6 +318,10 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
                     <code className="text-xs bg-muted px-1 rounded">http://localhost:4000</code>{' '}
                     or your server address.
                   </>
+                ) : isAnthropic ? (
+                  <>
+                    Custom base URL for Anthropic API proxy or gateway. Leave blank for default Anthropic API.
+                  </>
                 ) : (
                   <>
                     Custom base URL for OpenAI-compatible providers. Leave blank for OpenAI.
@@ -288,7 +355,42 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
                 )}
               </div>
 
-              {isLiteLLM || modelsData?.manualEntry ? (
+              {isAnthropic ? (
+                // Anthropic: fetch models from server (hardcoded list)
+                modelsLoading ? (
+                  <Skeleton className="h-10 w-full" />
+                ) : modelsData?.success && modelsData.models && modelsData.models.length > 0 ? (
+                  <Select onValueChange={field.onChange} value={field.value}>
+                    <FormControl>
+                      <SelectTrigger>
+                        <SelectValue placeholder="Select Claude model" />
+                      </SelectTrigger>
+                    </FormControl>
+                    <SelectContent>
+                      {categoryOrder
+                        .filter((cat) => groupedModels?.[cat]?.length)
+                        .map((category) => (
+                          <SelectGroup key={category}>
+                            <SelectLabel className="text-xs font-semibold text-muted-foreground">
+                              {categoryLabels[category] || category}
+                            </SelectLabel>
+                            {groupedModels?.[category]?.map((model) => (
+                              <SelectItem key={model.id} value={model.id}>
+                                {model.name}
+                              </SelectItem>
+                            ))}
+                          </SelectGroup>
+                        ))}
+                    </SelectContent>
+                  </Select>
+                ) : (
+                  <Input
+                    value={field.value}
+                    onChange={(e) => field.onChange(e.target.value)}
+                    placeholder="claude-sonnet-4-5-20250514"
+                  />
+                )
+              ) : isLiteLLM || modelsData?.manualEntry ? (
                 <Input
                   value={field.value}
                   onChange={(e) => field.onChange(e.target.value)}
@@ -341,7 +443,16 @@ export function AISettingsForm({ settings }: AISettingsFormProps) {
                 </Select>
               )}
               <FormDescription>
-                {isLiteLLM ? (
+                {isAnthropic ? (
+                  form.watch('ai_model')?.includes('opus') ? (
+                    <span className="flex items-center gap-1 text-amber-600">
+                      <SlidersHorizontal className="h-3 w-3" />
+                      Opus model — includes extended thinking for deeper analysis
+                    </span>
+                  ) : (
+                    'Anthropic Claude model to use for AI features'
+                  )
+                ) : isLiteLLM ? (
                   <>
                     Enter the model ID with the{' '}
                     <code className="text-xs bg-muted px-1 rounded">chatgpt/</code> prefix.