refactor: reorganize models to pkg/model and add authentication module

- Move ORM models from internal/model to pkg/model organized by module (auth/k8s/registry)
- Add authentication module with login, user management handlers
- Update all import paths to use new model locations
- Add frontend auth pages (Login, UserManagement) and authStore
- Remove deprecated internal/model/model.go

internal/module/k8s/handler.config.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"encoding/json"
 
-	"gitea.loveuer.com/loveuer/cluster/internal/model"
+	k8s "gitea.loveuer.com/loveuer/cluster/pkg/model/k8s"
 	"gitea.loveuer.com/loveuer/cluster/pkg/resp"
 	"gitea.loveuer.com/loveuer/cluster/pkg/store"
 	"github.com/gofiber/fiber/v3"
@@ -13,7 +13,7 @@ import (
 
 func ClusterConfigGet(ctx context.Context, db *gorm.DB, store store.Store) fiber.Handler {
 	return func(c fiber.Ctx) error {
-		var config model.ClusterConfig
+		var config k8s.ClusterConfig
 		
 		if err := db.Where("key = ?", "kubeconfig").First(&config).Error; err != nil {
 			if err == gorm.ErrRecordNotFound {
@@ -40,7 +40,7 @@ func ClusterConfigSet(ctx context.Context, db *gorm.DB, store store.Store) fiber
 			return resp.R400(c, "", nil, err)
 		}
 
-		config := model.ClusterConfig{
+		config := k8s.ClusterConfig{
 			Key:   "kubeconfig",
 			Value: req.Kubeconfig,
 		}