feat: add service catalog management with policy integration for domain-based resource access control

Add ServiceCatalogItem type and services CRUD API endpoints (list, create, update, delete). Extend Policy type to include services array with domain, upstream_ip, proxy_ip, and ports metadata.

Add ServicesPage component with table view and create/edit modals for managing service definitions. Include service name, domain, proxy, and upstream columns with port parsing logic.

Integrate service selection

backend/internal/httpserver/router.go

@@ -12,6 +12,7 @@ import (
 	"nexavpn/backend/internal/gateway"
 	"nexavpn/backend/internal/group"
 	"nexavpn/backend/internal/policy"
+	"nexavpn/backend/internal/servicecatalog"
 	"nexavpn/backend/internal/user"
 )
 
@@ -19,6 +20,7 @@ type Handlers struct {
 	Auth    *auth.Handler
 	User    *user.Handler
 	Device  *device.Handler
+	Service *servicecatalog.Handler
 	Policy  *policy.Handler
 	Gateway *gateway.Handler
 	Group   *group.Handler
@@ -68,6 +70,10 @@ func NewRouter(jwtSecret string, handlers Handlers) http.Handler {
 				r.Post("/groups", handlers.Group.Create)
 				r.Patch("/groups/{id}", handlers.Group.Update)
 				r.Delete("/groups/{id}", handlers.Group.Delete)
+				r.Get("/services", handlers.Service.List)
+				r.Post("/services", handlers.Service.Create)
+				r.Patch("/services/{id}", handlers.Service.Update)
+				r.Delete("/services/{id}", handlers.Service.Delete)
 				r.Get("/policies", handlers.Policy.List)
 				r.Post("/policies", handlers.Policy.Create)
 				r.Patch("/policies/{id}", handlers.Policy.Update)