docs(api): fix WebSocket path in async indexing docstring

Update docstring to use full versioned path /api/v1/ws/repos/{repo_id}/indexing
to match the actual registered endpoint and websocket_url response.

Author: DevanshuNEU

backend/routes/repos.py

@@ -348,7 +348,7 @@ async def index_repository_async(
     Trigger async indexing for a repository.
     
     Returns immediately with status 202. Connect to WebSocket at
-    /ws/repos/{repo_id}/indexing to receive real-time progress updates.
+    /api/v1/ws/repos/{repo_id}/indexing to receive real-time progress updates.
     """
     user_id = auth.user_id