🎨 style(query-editor): 收紧查询页标签与工具栏间距

- 去除主标签页与结果标签页默认下边距
- 缩小查询工具栏顶部留白
- 优化查询编辑器纵向空间利用
Refs #420

frontend/src/components/QueryEditor.tsx

@@ -2435,6 +2435,7 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
         }
         .query-result-tabs .ant-tabs-nav {
           flex: 0 0 auto;
+          margin: 0;
         }
         .query-result-tabs .ant-tabs-content-holder {
           flex: 1 1 auto;
@@ -2468,7 +2469,7 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
         }
       `}</style>
       <div ref={editorPaneRef}>
-      <div style={{ padding: '8px', display: 'flex', gap: '8px', flexShrink: 0, alignItems: 'center' }}>
+      <div style={{ padding: '4px 8px 8px', display: 'flex', gap: '8px', flexShrink: 0, alignItems: 'center' }}>
         <Select 
             style={{ width: 150 }} 
             placeholder="选择连接"

frontend/src/components/TabManager.tsx

@@ -285,6 +285,7 @@ const TabManager: React.FC = () => {
             }
             .main-tabs .ant-tabs-nav {
               flex: 0 0 auto;
+              margin: 0;
             }
             .main-tabs .ant-tabs-content-holder {
               flex: 1 1 auto;