✨ feat(saved-query): 支持已存查询后端持久化与连接重绑

- 后端新增 saved_queries.json 仓库，保存、导入、删除和重绑统一走 Wails 方法
- 启动时导入旧 lite-db-storage 中的 savedQueries 和连接快照，成功后清理旧字段
- 新增连接指纹匹配，唯一强匹配自动重绑，歧义场景保留为未匹配
- 侧边栏新增未匹配已存查询分组，并支持手动绑定到目标连接
- 前端保存、重命名、删除查询改为后端持久化，并补充浏览器 mock
- 补充后端与前端迁移回归测试

frontend/src/utils/secureConfigBootstrap.ts

@@ -12,6 +12,7 @@ import {
   readLegacyPersistedSecrets,
   stripLegacyPersistedSecrets,
 } from './legacyConnectionStorage';
+import { stripLegacySavedQueries } from './savedQueryPersistence';
 
 type StorageLike = Pick<Storage, 'getItem' | 'setItem' | 'removeItem'>;
 
@@ -312,8 +313,9 @@ const cleanupLegacySourceIfCompleted = (
   if (!storage || !rawPayload || status.overallStatus !== 'completed') {
     return;
   }
-  const sanitizedPayload = stripLegacyPersistedSecrets(rawPayload);
-  if (sanitizedPayload && sanitizedPayload !== rawPayload) {
+  const currentPayload = storage.getItem(LEGACY_PERSIST_KEY) ?? rawPayload;
+  const sanitizedPayload = stripLegacySavedQueries(stripLegacyPersistedSecrets(currentPayload));
+  if (sanitizedPayload && sanitizedPayload !== currentPayload) {
     storage.setItem(LEGACY_PERSIST_KEY, sanitizedPayload);
   }
 };