🐛 fix(sql-editor): 修复补全提示下连续输入光标跳转

- 调整 SQL 补全触发策略，避免普通字母输入高频触发 provider
- 支持 Monaco 补全取消 token，丢弃连续输入时的过期异步请求
- 将 SQL snippet provider 纳入统一 disposable 管理，避免重复注册残留
- 补充 QueryEditor 回归测试覆盖补全触发、取消和释放链路
Refs #504

frontend/src/components/QueryEditor.external-sql-save.test.tsx

@@ -71,6 +71,7 @@ const storeState = vi.hoisted(() => ({
   activeTabId: 'tab-1',
   aiPanelVisible: false,
   setAIPanelVisible: vi.fn(),
+  sqlSnippets: [] as any[],
 }));
 
 const backendApp = vi.hoisted(() => ({
@@ -827,6 +828,73 @@ describe('QueryEditor external SQL save', () => {
     renderer.unmount();
   });
 
+  it('registers all SQL completion providers in the disposable singleton state', async () => {
+    let renderer!: ReactTestRenderer;
+    await act(async () => {
+      renderer = create(<QueryEditor tab={createTab({ query: '' })} />);
+    });
+
+    const completionState = (globalThis as any).__gonaviSqlCompletionState;
+
+    expect(editorState.hoverProviders).toHaveLength(1);
+    expect(editorState.providers).toHaveLength(3);
+    expect(completionState.disposables).toHaveLength(4);
+
+    await act(async () => {
+      renderer.unmount();
+    });
+  });
+
+  it('keeps plain typing out of SQL completion trigger characters', async () => {
+    let renderer!: ReactTestRenderer;
+    await act(async () => {
+      renderer = create(<QueryEditor tab={createTab({ query: '' })} />);
+    });
+
+    const sqlProvider = editorState.providers.find((provider) => Array.isArray(provider.triggerCharacters) && provider.triggerCharacters.includes('.'));
+
+    expect(sqlProvider).toBeTruthy();
+    expect(sqlProvider.triggerCharacters).toEqual(['.']);
+    expect(sqlProvider.triggerCharacters).not.toContain('s');
+
+    await act(async () => {
+      renderer.unmount();
+    });
+  });
+
+  it('drops cancelled SQL completion requests while the user keeps typing', async () => {
+    let renderer!: ReactTestRenderer;
+    backendApp.DBGetTables.mockResolvedValueOnce({
+      success: true,
+      data: [{ Table: 'session_log' }],
+    });
+
+    await act(async () => {
+      renderer = create(<QueryEditor tab={createTab({ query: '', dbName: 'main' })} />);
+    });
+
+    const sqlProvider = editorState.providers.find((provider) => Array.isArray(provider.triggerCharacters) && provider.triggerCharacters.includes('.'));
+    expect(sqlProvider).toBeTruthy();
+
+    editorState.value = 'SELECT * FROM ss';
+    editorState.position = { lineNumber: 1, column: editorState.value.length + 1 };
+    editorState.latestOnChange?.(editorState.value);
+
+    const result = await sqlProvider.provideCompletionItems(
+      editorState.editor.getModel(),
+      editorState.position,
+      undefined,
+      { isCancellationRequested: true },
+    );
+
+    expect(result.suggestions).toEqual([]);
+    expect(backendApp.DBGetTables).not.toHaveBeenCalled();
+
+    await act(async () => {
+      renderer.unmount();
+    });
+  });
+
   it('keeps table name completion available after typing in a fresh query tab', async () => {
     let renderer!: ReactTestRenderer;
     autoFetchState.visible = true;