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/k8s.go

@@ -4,14 +4,14 @@ import (
 	"context"
 	"log"
 
-	"gitea.loveuer.com/loveuer/cluster/internal/model"
+	k8s "gitea.loveuer.com/loveuer/cluster/pkg/model/k8s"
 	"gitea.loveuer.com/loveuer/cluster/pkg/store"
 	"gorm.io/gorm"
 )
 
 func Init(ctx context.Context, db *gorm.DB, store store.Store) error {
 	if err := db.AutoMigrate(
-		&model.ClusterConfig{},
+		&k8s.ClusterConfig{},
 	); err != nil {
 		log.Fatalf("failed to migrate k8s database: %v", err)
 		return err