Remove UsecaseDependancies service locator pattern

Replace the UsecaseDependancies interface with plain Dependencies structs
defined locally in each route package. DeclareRoutes acts as the sole
composition root where use cases are resolved; sub-route functions and
controllers receive only the specific interfaces they need.

internal/app/admin.go

@@ -53,10 +53,21 @@ func NewAdmin(app *App) *Admin {
 	router := gin.New()
 	router.Use(gin.Logger(), gin.Recovery())
 
-	// Prepare usecases
+	// Prepare usecases (admin uses unrestricted provider access)
 	app.usecases.providerAdmin = providerUC.NewService(app.store)
 
-	admin.DeclareRoutes(app.cfg, router, app.store, app)
+	admin.DeclareRoutes(app.cfg, router, app.store, admin.Dependencies{
+		AuthUser:              app.usecases.authUser,
+		Domain:                app.usecases.domain,
+		Provider:              app.usecases.providerAdmin,
+		RemoteZoneImporter:    app.usecases.orchestrator.RemoteZoneImporter,
+		Service:               app.usecases.service,
+		User:                  app.usecases.user,
+		Zone:                  app.usecases.zone,
+		ZoneCorrectionApplier: app.usecases.orchestrator.ZoneCorrectionApplier,
+		ZoneImporter:          app.usecases.orchestrator.ZoneImporter,
+		ZoneService:           app.usecases.zoneService,
+	})
 	web.DeclareRoutes(app.cfg, router)
 
 	return &Admin{