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>

prisma/schema.prisma

@@ -350,6 +350,9 @@ model User {
   preferredWorkload Int?
   availabilityJson  Json?  @db.JsonB // { startDate?: string, endDate?: string }
 
+  // Test environment isolation
+  isTest Boolean @default(false)
+
   createdAt   DateTime  @default(now())
   updatedAt   DateTime  @updatedAt
   lastLoginAt DateTime?
@@ -494,6 +497,9 @@ model Program {
   description  String?
   settingsJson Json?         @db.JsonB
 
+  // Test environment isolation
+  isTest Boolean @default(false)
+
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
 
@@ -618,6 +624,9 @@ model Project {
   metadataJson    Json?    @db.JsonB // Custom fields from Typeform, etc.
   externalIdsJson Json?    @db.JsonB // Typeform ID, Notion ID, etc.
 
+  // Test environment isolation
+  isTest Boolean @default(false)
+
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
 
@@ -2090,6 +2099,9 @@ model Competition {
   notifyOnDeadlineApproach Boolean @default(true)
   deadlineReminderDays     Int[]   @default([7, 3, 1])
 
+  // Test environment isolation
+  isTest Boolean @default(false)
+
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
 
@@ -2104,6 +2116,7 @@ model Competition {
 
   @@index([programId])
   @@index([status])
+  @@index([isTest])
 }
 
 model Round {