refactor: redesign planos interface with design system patterns

- Create CreatePlanModal component with Headless UI Dialog
- Implement dark mode support throughout plans UI
- Update plans/page.tsx with professional card layout
- Update plans/[id]/page.tsx with consistent styling
- Add proper spacing, typography, and color consistency
- Implement smooth animations and transitions
- Add success/error message feedback
- Improve form UX with better input styling

backend/cmd/server/main.go

@@ -56,12 +56,15 @@ func main() {
 	companyRepo := repository.NewCompanyRepository(db)
 	signupTemplateRepo := repository.NewSignupTemplateRepository(db)
 	agencyTemplateRepo := repository.NewAgencyTemplateRepository(db)
+	planRepo := repository.NewPlanRepository(db)
+	subscriptionRepo := repository.NewSubscriptionRepository(db)
 
 	// Initialize services
 	authService := service.NewAuthService(userRepo, tenantRepo, cfg)
 	agencyService := service.NewAgencyService(userRepo, tenantRepo, cfg)
 	tenantService := service.NewTenantService(tenantRepo)
 	companyService := service.NewCompanyService(companyRepo)
+	planService := service.NewPlanService(planRepo, subscriptionRepo)
 
 	// Initialize handlers
 	healthHandler := handlers.NewHealthHandler()
@@ -70,6 +73,7 @@ func main() {
 	agencyHandler := handlers.NewAgencyRegistrationHandler(agencyService, cfg)
 	tenantHandler := handlers.NewTenantHandler(tenantService)
 	companyHandler := handlers.NewCompanyHandler(companyService)
+	planHandler := handlers.NewPlanHandler(planService)
 	signupTemplateHandler := handlers.NewSignupTemplateHandler(signupTemplateRepo, userRepo, tenantRepo, agencyService)
 	agencyTemplateHandler := handlers.NewAgencyTemplateHandler(agencyTemplateRepo, agencyService, userRepo, tenantRepo)
 	filesHandler := handlers.NewFilesHandler(cfg)
@@ -112,6 +116,10 @@ func main() {
 	router.HandleFunc("/api/signup-templates/slug/{slug}", signupTemplateHandler.GetTemplateBySlug).Methods("GET")
 	router.HandleFunc("/api/signup/register", signupTemplateHandler.PublicRegister).Methods("POST")
 	
+	// Public plans (for signup flow)
+	router.HandleFunc("/api/plans", planHandler.ListActivePlans).Methods("GET")
+	router.HandleFunc("/api/plans/{id}", planHandler.GetActivePlan).Methods("GET")
+	
 	// File upload (public for signup, will also work with auth)
 	router.HandleFunc("/api/upload", uploadHandler.Upload).Methods("POST")
 
@@ -156,6 +164,9 @@ func main() {
 		}
 	}))).Methods("GET", "PUT", "PATCH", "DELETE")
 
+	// SUPERADMIN: Plans management
+	planHandler.RegisterRoutes(router)
+
 	// ADMIN_AGENCIA: Client registration
 	router.Handle("/api/agencies/clients/register", authMiddleware(http.HandlerFunc(agencyHandler.RegisterClient))).Methods("POST")