fix(db): pre-check too-new DB before schema writes; exit on close in recovery mode

Addresses review feedback on the too-new-DB recovery flow.

- P1: stored_user_version_exceeds_supported() is now checked BEFORE
  Database::init(), so create_tables()'s DDL (incl. the unconditional
  DROP INDEX/DROP TABLE IF EXISTS failover_queue) never runs against a
  database whose user_version we cannot understand. The earlier
  post-init-failure recovery branch is removed; the pre-check is the
  single authoritative guard, so "don't write to a DB we can't read"
  now holds from the very first DB access.

- P2: the window CloseRequested handler now detects recovery mode
  (init_error kind = db_version_too_new) and exits the app instead of
  honoring minimize_to_tray_on_close. Recovery mode returns before the
  tray is created, so hiding the window would leave the app running with
  no tray to bring it back; native-close now quits cleanly.

Verified: cargo fmt --check clean; cross-model Rust review of both fixes
(compile-correctness + no normal-startup/close regression).

src-tauri/src/lib.rs

@@ -270,6 +270,16 @@ pub fn run() {
         // 拦截窗口关闭：根据设置决定是否最小化到托盘
         .on_window_event(|window, event| {
             if let tauri::WindowEvent::CloseRequested { api, .. } = event {
+                // 数据库版本过新的恢复模式下没有托盘可唤回，关闭即退出，避免应用隐身后台
+                let in_db_recovery = crate::init_status::get_init_error()
+                    .map(|p| p.kind.as_deref() == Some("db_version_too_new"))
+                    .unwrap_or(false);
+                if in_db_recovery {
+                    api.prevent_close();
+                    window.app_handle().exit(0);
+                    return;
+                }
+
                 let settings = crate::settings::get_settings();
 
                 if settings.minimize_to_tray_on_close {
@@ -403,39 +413,41 @@ pub fn run() {
             // 说明：从 v3.8.* 升级的用户通常会走到这里的 SQLite schema 迁移，
             // 若迁移失败（数据库损坏/权限不足/user_version 过新等），需要给用户明确提示，
             // 否则表现可能只是“应用打不开/闪退”。
+            //
+            // 预检：数据库版本过新时，必须先于任何 schema 写操作（create_tables 内含
+            // DROP/ALTER 等 DDL）进入恢复界面，避免旧应用对读不懂的更新版 DB 落写。
+            match crate::database::Database::stored_user_version_exceeds_supported(&db_path) {
+                Ok(Some(version)) => {
+                    log::warn!("数据库版本过新（v{version}），引导用户在应用内升级应用");
+                    crate::init_status::set_init_error(crate::init_status::InitErrorPayload {
+                        path: db_path.display().to_string(),
+                        error: format!(
+                            "数据库版本过新（{version}），当前应用仅支持 {}，请升级应用后再尝试。",
+                            crate::database::SCHEMA_VERSION
+                        ),
+                        kind: Some("db_version_too_new".to_string()),
+                        db_version: Some(version),
+                        supported_version: Some(crate::database::SCHEMA_VERSION),
+                    });
+                    // 主窗口默认 visible:false，恢复界面必须强制显示
+                    if let Some(window) = app.get_webview_window("main") {
+                        let _ = window.show();
+                        let _ = window.set_focus();
+                    }
+                    return Ok(());
+                }
+                Ok(None) => {}
+                Err(e) => {
+                    log::warn!("预检数据库版本失败，继续正常初始化流程: {e}");
+                }
+            }
+
             let db = loop {
                 match crate::database::Database::init() {
                     Ok(db) => break Arc::new(db),
                     Err(e) => {
                         log::error!("Failed to init database: {e}");
 
-                        // 数据库版本过新（应用过旧）：无法向下迁移，反复重试也无效。
-                        // 记录可恢复错误并进入应用内「升级应用」恢复界面，而不是死循环弹窗。
-                        if let Ok(Some(version)) =
-                            crate::database::Database::stored_user_version_exceeds_supported(
-                                &db_path,
-                            )
-                        {
-                            log::warn!("数据库版本过新（v{version}），引导用户在应用内升级应用");
-                            crate::init_status::set_init_error(
-                                crate::init_status::InitErrorPayload {
-                                    path: db_path.display().to_string(),
-                                    error: e.to_string(),
-                                    kind: Some("db_version_too_new".to_string()),
-                                    db_version: Some(version),
-                                    supported_version: Some(
-                                        crate::database::SCHEMA_VERSION,
-                                    ),
-                                },
-                            );
-                            // 主窗口默认 visible:false，恢复界面必须强制显示
-                            if let Some(window) = app.get_webview_window("main") {
-                                let _ = window.show();
-                                let _ = window.set_focus();
-                            }
-                            return Ok(());
-                        }
-
                         if !show_database_init_error_dialog(app.handle(), &db_path, &e.to_string())
                         {
                             log::info!("用户选择退出程序");