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/adapter/input/http/rest/utils.go

@@ -3,7 +3,7 @@ package rest
 import (
 	"encoding/json"
 	"net/http"
-	
+
 	"github.com/ocdp/cluster-service/internal/adapter/input/http/dto"
 )
 
@@ -32,4 +32,3 @@ func respondSuccess(w http.ResponseWriter, message string, data interface{}) {
 	}
 	respondJSON(w, http.StatusOK, response)
 }
-