feat(backup): add hourly periodic backup timer during runtime

Previously periodic backup only checked on startup. Now spawns a
tokio interval task that checks every hour while the app is running.

src-tauri/src/lib.rs

@@ -769,10 +769,24 @@ pub fn run() {
                 // 检查 settings 表中的代理状态，自动恢复代理服务
                 restore_proxy_state_on_startup(&state).await;
 
-                // Periodic backup check
+                // Periodic backup check (on startup)
                 if let Err(e) = state.db.periodic_backup_if_needed() {
                     log::warn!("Periodic backup failed on startup: {e}");
                 }
+
+                // Periodic backup timer: check every hour while the app is running
+                let db_for_timer = state.db.clone();
+                tauri::async_runtime::spawn(async move {
+                    let mut interval =
+                        tokio::time::interval(std::time::Duration::from_secs(3600));
+                    interval.tick().await; // skip immediate first tick (already checked above)
+                    loop {
+                        interval.tick().await;
+                        if let Err(e) = db_for_timer.periodic_backup_if_needed() {
+                            log::warn!("Periodic backup timer failed: {e}");
+                        }
+                    }
+                });
             });
 
             // Linux: 禁用 WebKitGTK 硬件加速，防止 EGL 初始化失败导致白屏