🐛 fix(query-editor): 修复大字号表候选下划线裁剪 (#829)

## 背景

SQL 查询编辑器的表候选项使用 Monaco 原生双行布局，行高固定为 18px + 18px。

当编辑器字号调整为 18px 或 20px 时，表名中的下划线和字母下行部分可能被候选项行高裁剪。

## 变更内容

- 新增 SQL 候选项布局计算逻辑，根据最终编辑器字号动态计算表名行高和候选项总高度。
- 将 Monaco 的 `suggestLineHeight` 与动态布局保持一致。
- 使用 CSS 变量替代候选项中的固定行高，确保大字号下内容完整显示。
- 保持默认字号下原有 36px 候选项高度不变。
- 增加默认字号、大字号和显式字号配置的单元测试。

## 影响范围

- 仅影响 v2 SQL 查询编辑器的表候选项。
- 旧版编辑器和其他类型的 Monaco 编辑器不受影响。
- 不涉及数据结构、接口、数据库或构建配置变更。
- SQL 字号为 18px 时，候选项高度调整为 43px；20px 时调整为 46px。

## 验证方式

- `sqlEditorTypography.test.ts`：3 个测试通过。
- `MonacoEditor.typography.test.tsx`：6 个测试通过。
- TypeScript 类型检查通过：`npx tsc --noEmit`。
- `git diff --check 630ba7fc^ 630ba7fc` 通过。

frontend/src/utils/sqlEditorTypography.test.ts

@@ -3,6 +3,7 @@ import { describe, expect, it } from 'vitest';
 import {
   migrateLegacySqlEditorTypographySettings,
   resolveSqlEditorFontSize,
+  resolveSqlEditorSuggestionLayout,
   sanitizeSqlEditorTypographySettings,
 } from './sqlEditorTypography';
 
@@ -39,4 +40,22 @@ describe('SQL editor typography', () => {
       sqlEditorFontSizeFollowGlobal: false,
     });
   });
+
+  it('keeps default completion rows unchanged and grows the table-name row for large fonts', () => {
+    expect(resolveSqlEditorSuggestionLayout(13)).toEqual({
+      nameLineHeight: 18,
+      commentLineHeight: 18,
+      rowHeight: 36,
+    });
+    expect(resolveSqlEditorSuggestionLayout(18)).toEqual({
+      nameLineHeight: 25,
+      commentLineHeight: 18,
+      rowHeight: 43,
+    });
+    expect(resolveSqlEditorSuggestionLayout(20)).toEqual({
+      nameLineHeight: 28,
+      commentLineHeight: 18,
+      rowHeight: 46,
+    });
+  });
 });

frontend/src/utils/sqlEditorTypography.ts

@@ -6,6 +6,14 @@ export interface SqlEditorTypographySettings {
 export const MIN_SQL_EDITOR_FONT_SIZE = 10;
 export const MAX_SQL_EDITOR_FONT_SIZE = 20;
 export const DEFAULT_SQL_EDITOR_FONT_SCALE = 0.92;
+export const SQL_EDITOR_SUGGESTION_COMMENT_LINE_HEIGHT = 18;
+export const SQL_EDITOR_SUGGESTION_NAME_LINE_HEIGHT_SCALE = 1.4;
+
+export interface SqlEditorSuggestionLayout {
+  nameLineHeight: number;
+  commentLineHeight: number;
+  rowHeight: number;
+}
 
 export const DEFAULT_SQL_EDITOR_TYPOGRAPHY_SETTINGS: SqlEditorTypographySettings = {
   sqlEditorFontSize: null,
@@ -45,6 +53,26 @@ export const resolveSqlEditorFontSize = ({
   return sanitizeSqlEditorFontSize(sqlEditorFontSize) ?? globalDerivedFontSize;
 };
 
+/**
+ * Keep the structured table completion label tall enough for the editor font's
+ * descenders while preserving the existing 18px + 18px layout at default sizes.
+ */
+export const resolveSqlEditorSuggestionLayout = (fontSize: unknown): SqlEditorSuggestionLayout => {
+  const normalizedFontSize = Number.isFinite(Number(fontSize))
+    ? Math.max(MIN_SQL_EDITOR_FONT_SIZE, Math.round(Number(fontSize)))
+    : 14;
+  const nameLineHeight = Math.max(
+    SQL_EDITOR_SUGGESTION_COMMENT_LINE_HEIGHT,
+    Math.round(normalizedFontSize * SQL_EDITOR_SUGGESTION_NAME_LINE_HEIGHT_SCALE),
+  );
+  const commentLineHeight = SQL_EDITOR_SUGGESTION_COMMENT_LINE_HEIGHT;
+  return {
+    nameLineHeight,
+    commentLineHeight,
+    rowHeight: nameLineHeight + commentLineHeight,
+  };
+};
+
 export const sanitizeSqlEditorTypographySettings = (
   value: Partial<SqlEditorTypographySettings> | undefined,
 ): SqlEditorTypographySettings => {