fix: 接入备份维护钩子并补齐 SQLX 缓存

- ProcessManager 新增 has_instance_process（备份启动守卫依赖）

- 删除/启动/编辑/迁移目录时接入备份维护钩子（lock_instance_maintenance + begin_instance_deletion + delete_instance_backups），remove_instance 拆出 remove_instance_files_and_state

- run 启动前检查活跃备份操作并加维护锁

- 目录迁移时搬移默认备份仓库并入队清理

- 更新 settings SELECT 的 SQLX 离线缓存（补 ui_font/backup_repository_path/mono_font）

- create_recorded_symlink 非 Windows 未用参数加 cfg_attr 豁免

packages/app-lib/src/state/dirs.rs

@@ -363,6 +363,32 @@ impl DirectoryInfo {
                     return Err(crate::ErrorKind::DirectoryMoveError(format!("Cannot move directory to {}: directory is not writable", move_dir.display())).into());
                 }
 
+                // If the user hasn't chosen a custom backup repository, the
+                // default one lives next to the launcher data. Move it along
+                // with the rest of the directory and queue a cleanup of the
+                // old copy on next startup.
+                if settings.backup_repository_path.is_none() {
+                    let old_repository =
+                        prev_dir.join("Backups").join("instances");
+                    let new_repository =
+                        move_dir.join("Backups").join("instances");
+                    if let Some(path) = crate::api::instance::move_default_repository_for_launcher_directory(
+                        &old_repository,
+                        &new_repository,
+                    )
+                    .await?
+                    {
+                        sqlx::query(
+                            "INSERT INTO pending_backup_repository_cleanups (path, created_at)
+                             VALUES (?, unixepoch('subsec') * 1000)
+                             ON CONFLICT(path) DO UPDATE SET created_at = excluded.created_at",
+                        )
+                        .bind(path.to_string_lossy().to_string())
+                        .execute(exec)
+                        .await?;
+                    }
+                }
+
                 const MOVE_DIRS: &[&str] = &[
                     CACHES_FOLDER_NAME,
                     INSTANCES_FOLDER_NAME,