fn bubble_position_path(app: &AppHandle) -> Option<PathBuf>Expand description
Persisted-position file path: <app-config-dir>/bubble-position.txt.
The format is "{x},{y}\n" — two integers + a comma + a newline.
We deliberately avoid serde_json (no new workspace dep) and
avoid TOML (overkill for two integers); the file is human-readable
- trivially repairable + small enough to parse by hand.