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>

prisma/migrations/20260221100000_add_anthropic_provider_remove_locale/migration.sql

@@ -0,0 +1,13 @@
+-- Delete any existing LOCALIZATION settings
+DELETE FROM "SystemSettings" WHERE category = 'LOCALIZATION';
+
+-- Add provider field to AIUsageLog for cross-provider cost tracking
+ALTER TABLE "AIUsageLog" ADD COLUMN "provider" TEXT;
+
+-- Remove LOCALIZATION from SettingCategory enum
+-- First create new enum without the value, then swap
+CREATE TYPE "SettingCategory_new" AS ENUM ('AI', 'BRANDING', 'EMAIL', 'STORAGE', 'SECURITY', 'DEFAULTS', 'WHATSAPP', 'AUDIT_CONFIG', 'DIGEST', 'ANALYTICS', 'INTEGRATIONS', 'COMMUNICATION', 'FEATURE_FLAGS');
+ALTER TABLE "SystemSettings" ALTER COLUMN "category" TYPE "SettingCategory_new" USING ("category"::text::"SettingCategory_new");
+ALTER TYPE "SettingCategory" RENAME TO "SettingCategory_old";
+ALTER TYPE "SettingCategory_new" RENAME TO "SettingCategory";
+DROP TYPE "SettingCategory_old";