fix: normalize backslashes in include_paths validator

Defensive measure -- converts Windows-style backslashes to forward
slashes before validation. Costs nothing, prevents edge cases if
infra or client platform changes.

Author: DevanshuNEU

backend/routes/repos.py

@@ -471,7 +471,7 @@ def sanitize_paths(cls, v: Optional[List[str]]) -> Optional[List[str]]:
         for item in v:
             if not isinstance(item, str):
                 raise ValueError(f"include_paths entries must be strings, got {type(item).__name__}")
-            item = item.strip().strip("/")
+            item = item.replace("\\", "/").strip().strip("/")
             if not item:
                 raise ValueError("include_paths entries must not be empty")
             if ".." in item.split("/"):