🐛 fix(mongodb/query-editor): 修复受限账号连接与不限行数

- MongoDB 指定数据库时保留连接校验并跳过全库枚举
- 允许查询最大行数为 0 并持久化不限设置
- 补充数据库枚举与不限行数持久化回归测试

Refs #741
Refs #752

frontend/src/store.test.ts

@@ -314,6 +314,23 @@ describe('store appearance persistence', () => {
     expect(reloaded.useStore.getState().queryOptions.wordWrap).toBe(true);
   });
 
+  it('persists zero as the unlimited SQL query row limit', async () => {
+    const { useStore } = await importStore();
+
+    useStore.getState().setQueryOptions({ maxRows: 0 });
+    expect(useStore.getState().queryOptions.maxRows).toBe(0);
+
+    const persisted = JSON.parse(storage.getItem('lite-db-storage') || '{}');
+    expect(persisted.state.queryOptions.maxRows).toBe(0);
+
+    vi.resetModules();
+    const reloaded = await importStore();
+    expect(reloaded.useStore.getState().queryOptions.maxRows).toBe(0);
+
+    reloaded.useStore.getState().setQueryOptions({ maxRows: -1 });
+    expect(reloaded.useStore.getState().queryOptions.maxRows).toBe(5000);
+  });
+
   it('persists the table overview view mode across store reloads', async () => {
     const { useStore } = await importStore();
     expect(useStore.getState().queryOptions.tableOverviewViewMode).toBeUndefined();

frontend/src/store.ts

@@ -2794,7 +2794,7 @@ const sanitizeQueryOptions = (value: unknown): QueryOptions => {
   const queryEditorEditorHeightRatio = sanitizeQueryEditorEditorHeightRatio(
     raw.queryEditorEditorHeightRatio,
   );
-  if (!Number.isFinite(maxRows) || maxRows <= 0) {
+  if (!Number.isFinite(maxRows) || maxRows < 0) {
     return {
       maxRows: 5000,
       wordWrap,