feat: add persistent lifetime stats and sync achievements

- Add lifetime stats persistence to Rust backend
- Sync achievement state between frontend and backend on startup
- Add commands for loading/saving stats to disk
- Expand achievement definitions with 150+ new achievements
- Fix stats store to properly track total vs session metrics

src-tauri/src/lib.rs

@@ -95,6 +95,7 @@ pub fn run() {
             get_config,
             save_config,
             get_usage_stats,
+            get_persisted_stats,
             load_saved_achievements,
             answer_question,
             send_windows_notification,