🐛 fix(query-editor): 修复切换查询页后 SQL 美化方言误判

- 同步查询页的 connectionId 与 dbName 状态
- 美化时按活动连接和 tab 上下文兜底选择格式化方言
- 补充 PostgreSQL ::date 场景回归测试
Close #494

frontend/src/components/QueryEditor.tsx

@@ -2047,6 +2047,19 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
       currentDbRef.current = currentDb;
   }, [currentDb]);
 
+  useEffect(() => {
+      const nextConnectionId = String(tab.connectionId || '').trim();
+      const nextDb = String(tab.dbName || '').trim();
+      if (nextConnectionId !== currentConnectionIdRef.current) {
+          currentConnectionIdRef.current = nextConnectionId;
+          setCurrentConnectionId(nextConnectionId);
+      }
+      if (nextDb !== currentDbRef.current) {
+          currentDbRef.current = nextDb;
+          setCurrentDb(nextDb);
+      }
+  }, [tab.id, tab.connectionId, tab.dbName]);
+
   useEffect(() => {
       if (isExternalSQLFileTab) return;
       const currentDraft = getQueryTabDraft(tab.id, query);
@@ -3704,7 +3717,13 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
 
   const handleFormat = () => {
       try {
-          const formatterLanguage = resolveQueryEditorFormatterLanguage(connections.find(c => c.id === currentConnectionId));
+          const activeConnectionId = String(currentConnectionIdRef.current || '').trim();
+          const tabConnectionId = String(tab.connectionId || '').trim();
+          const conn = connectionsRef.current.find(c => c.id === activeConnectionId)
+              || (tabConnectionId && tabConnectionId !== activeConnectionId
+                  ? connectionsRef.current.find(c => c.id === tabConnectionId)
+                  : undefined);
+          const formatterLanguage = resolveQueryEditorFormatterLanguage(conn);
           const formatted = format(getCurrentQuery(), { language: formatterLanguage, keywordCase: sqlFormatOptions.keywordCase });
           const editor = editorRef.current;
           const monaco = monacoRef.current;