refactor: full-stack restructure with multi-tenancy, workspace management, and K8s diagnostics

- Add Workspace domain (entity, repository, service, handler, DTO)
- Add multi-tenant K8s client with tenant binding and quota management
- Add K8s diagnostics client (instance diagnostics)
- Add authorization middleware (authz package)
- Restructure frontend to feature-based architecture (features/)
- Add User Management page in configuration
- Add AccessDenied page and route guards
- Refactor shared components (form inputs, layout, UI)
- Update Tailwind config for new design system
- Add comprehensive documentation (docs/, tasks/, plans)
- Improve cluster service with better kubeconfig handling
- Add tests for crypto, config, helm client, tenant binding

backend/internal/domain/entity/registry.go

@@ -7,6 +7,9 @@ import (
 // Registry OCI Registry 领域实体
 type Registry struct {
 	ID          string
+	WorkspaceID string
+	OwnerID     string
+	Visibility  string
 	Name        string
 	URL         string
 	Description string
@@ -21,10 +24,11 @@ type Registry struct {
 func NewRegistry(name, url string) *Registry {
 	now := time.Now()
 	return &Registry{
-		Name:      name,
-		URL:       url,
-		CreatedAt: now,
-		UpdatedAt: now,
+		Name:       name,
+		URL:        url,
+		Visibility: "private",
+		CreatedAt:  now,
+		UpdatedAt:  now,
 	}
 }
 
@@ -55,6 +59,8 @@ func (r *Registry) Validate() error {
 	if r.URL == "" {
 		return ErrInvalidRegistryURL
 	}
+	if r.Visibility == "" {
+		r.Visibility = "private"
+	}
 	return nil
 }
-