Add Anthropic API, test environment, remove locale settings

Feature 1: Anthropic API Integration
- 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

Feature 2: Remove Locale Settings UI
- Strip Localization tab from admin settings
- Remove i18n settings from router inferCategory and getFeatureFlags
- Keep franc document language detection intact

Feature 3: Test Environment with Role Impersonation
- Add isTest field to User, Program, Project, Competition models
- Test environment service: create/teardown with realistic dummy data
- JWT-based impersonation for test users (@test.local emails)
- Impersonation banner with quick-switch between test roles
- Test environment panel in admin settings (SUPER_ADMIN only)
- Email redirect: @test.local emails routed to admin with [TEST] prefix
- Complete data isolation: 45+ isTest:false filters across platform
  - All global queries on User/Project/Program/Competition
  - AI services blocked from processing test data
  - Cron jobs skip test rounds/users
  - Analytics/exports exclude test data
  - Admin layout/pickers hide test programs

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

src/lib/auth.config.ts

@@ -10,6 +10,11 @@ declare module 'next-auth' {
       name?: string | null
       role: UserRole
       mustSetPassword?: boolean
+      // Impersonation fields
+      isImpersonating?: boolean
+      realUserId?: string
+      realRole?: UserRole
+      impersonatedName?: string | null
     }
   }
 
@@ -24,6 +29,12 @@ declare module '@auth/core/jwt' {
     id: string
     role: UserRole
     mustSetPassword?: boolean
+    // Impersonation fields
+    impersonatedUserId?: string
+    impersonatedRole?: UserRole
+    impersonatedName?: string | null
+    realUserId?: string
+    realRole?: UserRole
   }
 }