fix broken import

vms/tabs/__init__.py

@@ -2,6 +2,7 @@
 Tab components for Video Model Studio UI
 """
 
+from .base_tab import BaseTab
 from .import_tab import ImportTab
 from .split_tab import SplitTab
 from .caption_tab import CaptionTab
@@ -11,6 +12,7 @@ from .preview_tab import PreviewTab
 from .manage_tab import ManageTab
 
 __all__ = [
+    'BaseTab',
     'ImportTab',
     'SplitTab',
     'CaptionTab',

vms/tabs/preview_tab.py

@@ -7,7 +7,7 @@ import logging
 from pathlib import Path
 from typing import Dict, Any, List, Optional, Tuple
 
-from vms.services.base_tab import BaseTab
+from vms.tabs import BaseTab
 from vms.config import (
     MODEL_TYPES, DEFAULT_PROMPT_PREFIX
 )