style: apply ruff format and extend gitignore

Ruff auto-fixes import order and line wrapping. Gitignore covers
build artifacts and coverage output from future test runs.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/worker.py

@@ -70,9 +70,7 @@ def _is_ignored_name(name: str) -> bool:
     """Skip Syncthing metadata/temp files and other dotfiles."""
     if name.startswith("."):
         return True
-    if name.startswith(".syncthing.") or ".syncthing." in name:
-        return True
-    return False
+    return bool(name.startswith(".syncthing.") or ".syncthing." in name)
 
 
 def _is_stable(path: Path) -> bool: