Renamed to "Proton WireGuard Exporter".

Added
- Stop button to interrupt a running export.
- Download history: previously exported servers are skipped on subsequent runs.
- "Clear download history" button to reset that history.
- Progress bar with current / total / percentage.
- App-version header is now editable in the UI.

Improved
- Session UID and private key are stored in extension-local storage instead of localStorage.
- Cleaner, system-font UI; no remote font imports.
- Better error messages on HTTP 401 (expired session) and HTTP 429 (rate limit, with automatic backoff).
- Cross-browser compatibility (Firefox + Chromium MV3).