fix: Restore all files lost during destructive rebase

A previous `git pull --rebase origin main` dropped 177 local commits,
losing 3400+ files across admin-v2, backend, studio-v2, website,
klausur-service, and many other services. The partial restore attempt
(660295e2) only recovered some files.

This commit restores all missing files from pre-rebase ref 98933f5e
while preserving post-rebase additions (night-scheduler, night-mode UI,
NightModeWidget dashboard integration).

Restored features include:
- AI Module Sidebar (FAB), OCR Labeling, OCR Compare
- GPU Dashboard, RAG Pipeline, Magic Help
- Klausur-Korrektur (8 files), Abitur-Archiv (5+ files)
- Companion, Zeugnisse-Crawler, Screen Flow
- Full backend, studio-v2, website, klausur-service
- All compliance SDKs, agent-core, voice-service
- CI/CD configs, documentation, scripts

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

billing-service/cmd/server/main.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"log"
+
+	"github.com/breakpilot/billing-service/internal/config"
+	"github.com/breakpilot/billing-service/internal/database"
+	"github.com/breakpilot/billing-service/internal/handlers"
+	"github.com/breakpilot/billing-service/internal/middleware"
+	"github.com/breakpilot/billing-service/internal/services"
+	"github.com/gin-gonic/gin"
+)
+
+func main() {
+	// Load configuration
+	cfg, err := config.Load()
+	if err != nil {
+		log.Fatalf("Failed to load config: %v", err)
+	}
+
+	// Initialize database
+	db, err := database.Connect(cfg.DatabaseURL)
+	if err != nil {
+		log.Fatalf("Failed to connect to database: %v", err)
+	}
+	defer db.Close()
+
+	// Run migrations
+	if err := database.Migrate(db); err != nil {
+		log.Fatalf("Failed to run migrations: %v", err)
+	}
+
+	// Setup Gin router
+	if cfg.Environment == "production" {
+		gin.SetMode(gin.ReleaseMode)
+	}
+
+	router := gin.Default()
+
+	// Global middleware
+	router.Use(middleware.CORS())
+	router.Use(middleware.RequestLogger())
+	router.Use(middleware.RateLimiter())
+
+	// Health check (no auth required)
+	router.GET("/health", func(c *gin.Context) {
+		c.JSON(200, gin.H{
+			"status":  "healthy",
+			"service": "billing-service",
+			"version": "1.0.0",
+		})
+	})
+
+	// Initialize services
+	subscriptionService := services.NewSubscriptionService(db)
+
+	// Create Stripe service (mock or real depending on config)
+	var stripeService *services.StripeService
+	if cfg.IsMockMode() {
+		log.Println("Starting in MOCK MODE - Stripe API calls will be simulated")
+		stripeService = services.NewMockStripeService(
+			cfg.BillingSuccessURL,
+			cfg.BillingCancelURL,
+			cfg.TrialPeriodDays,
+			subscriptionService,
+		)
+	} else {
+		stripeService = services.NewStripeService(
+			cfg.StripeSecretKey,
+			cfg.StripeWebhookSecret,
+			cfg.BillingSuccessURL,
+			cfg.BillingCancelURL,
+			cfg.TrialPeriodDays,
+			subscriptionService,
+		)
+	}
+
+	entitlementService := services.NewEntitlementService(db, subscriptionService)
+	usageService := services.NewUsageService(db, entitlementService)
+
+	// Initialize handlers
+	billingHandler := handlers.NewBillingHandler(
+		db,
+		subscriptionService,
+		stripeService,
+		entitlementService,
+		usageService,
+	)
+	webhookHandler := handlers.NewWebhookHandler(
+		db,
+		cfg.StripeWebhookSecret,
+		subscriptionService,
+		entitlementService,
+	)
+
+	// API v1 routes
+	v1 := router.Group("/api/v1/billing")
+	{
+		// Stripe webhook (no auth - uses Stripe signature)
+		v1.POST("/webhook", webhookHandler.HandleStripeWebhook)
+
+		// =============================================
+		// User Endpoints (require JWT auth)
+		// =============================================
+		user := v1.Group("")
+		user.Use(middleware.AuthMiddleware(cfg.JWTSecret))
+		{
+			// Subscription status and management
+			user.GET("/status", billingHandler.GetBillingStatus)
+			user.GET("/plans", billingHandler.GetPlans)
+			user.POST("/trial/start", billingHandler.StartTrial)
+			user.POST("/change-plan", billingHandler.ChangePlan)
+			user.POST("/cancel", billingHandler.CancelSubscription)
+			user.GET("/portal", billingHandler.GetCustomerPortal)
+		}
+
+		// =============================================
+		// Internal Endpoints (service-to-service)
+		// =============================================
+		internal := v1.Group("")
+		internal.Use(middleware.InternalAPIKeyMiddleware(cfg.InternalAPIKey))
+		{
+			// Entitlements
+			internal.GET("/entitlements/:userId", billingHandler.GetEntitlements)
+			internal.GET("/entitlements/check/:userId/:feature", billingHandler.CheckEntitlement)
+
+			// Usage tracking
+			internal.POST("/usage/track", billingHandler.TrackUsage)
+			internal.GET("/usage/check/:userId/:type", billingHandler.CheckUsage)
+		}
+	}
+
+	// Start server
+	port := cfg.Port
+	if port == "" {
+		port = "8083"
+	}
+
+	log.Printf("Starting Billing Service on port %s", port)
+	if err := router.Run(":" + port); err != nil {
+		log.Fatalf("Failed to start server: %v", err)
+	}
+}