✨ feat(sql-editor): 增加SQL错误中文语义提示

- 新增 SQL 执行错误语义化规则，覆盖语法、对象、字段、约束和连接类错误

- 执行失败和刷新失败展示中文语义、处理建议与原始错误

- 补充工具函数与 QueryEditor 回归测试，确保英文报错可读化

frontend/src/utils/sqlErrorSemantics.test.ts

@@ -0,0 +1,46 @@
+import { describe, expect, it } from 'vitest';
+
+import { formatSqlExecutionError } from './sqlErrorSemantics';
+
+describe('formatSqlExecutionError', () => {
+  it('adds Chinese semantic explanation for SQL syntax errors and keeps raw text', () => {
+    const formatted = formatSqlExecutionError('pq: syntax error at or near "from"');
+
+    expect(formatted).toContain('中文语义：SQL 语法错误');
+    expect(formatted).toContain('处理建议：');
+    expect(formatted).toContain('原始错误：pq: syntax error at or near "from"');
+  });
+
+  it('recognizes missing table errors', () => {
+    const formatted = formatSqlExecutionError('ERROR: relation "orders" does not exist');
+
+    expect(formatted).toContain('中文语义：表或对象不存在');
+    expect(formatted).toContain('原始错误：ERROR: relation "orders" does not exist');
+  });
+
+  it('recognizes duplicate key errors with statement prefix', () => {
+    const formatted = formatSqlExecutionError('Duplicate entry "1" for key "PRIMARY"', {
+      prefix: '第 2 条语句执行失败：',
+    });
+
+    expect(formatted.startsWith('第 2 条语句执行失败：\n中文语义：唯一约束或主键冲突')).toBe(true);
+    expect(formatted).toContain('原始错误：Duplicate entry "1" for key "PRIMARY"');
+  });
+
+  it('falls back to a generic database execution error', () => {
+    const formatted = formatSqlExecutionError('driver returned unexpected status 123');
+
+    expect(formatted).toContain('中文语义：数据库执行错误');
+    expect(formatted).toContain('原始错误：driver returned unexpected status 123');
+  });
+
+  it('does not format an already formatted message again', () => {
+    const raw = [
+      '中文语义：SQL 语法错误。通常是关键字、逗号、括号、引号、语句顺序或当前数据库方言不匹配。',
+      '处理建议：检查报错位置附近的 SQL 片段，并确认当前连接的数据源类型与 SQL 方言一致。',
+      '原始错误：pq: syntax error at or near "from"',
+    ].join('\n');
+
+    expect(formatSqlExecutionError(raw)).toBe(raw);
+  });
+});