✨ feat(ddl): 为 DDL 视图增加按方言格式化展示能力

- 新增通用 DDL 格式化工具
- DataGrid 查看 DDL 时按数据源方言输出可读 SQL
- 覆盖 DuckDB DDL 展示与工具层测试

frontend/src/utils/ddlFormat.test.ts

@@ -0,0 +1,22 @@
+import { describe, expect, it } from 'vitest';
+
+import { formatDdlForDisplay } from './ddlFormat';
+
+describe('formatDdlForDisplay', () => {
+  it('formats DuckDB create table SQL into multiline output', () => {
+    const raw = 'CREATE TABLE customers(customer_id BIGINT, customer_code VARCHAR, city VARCHAR, tier VARCHAR, signup_date DATE, lifetime_value DECIMAL(12,2), PRIMARY KEY(customer_id));';
+
+    const formatted = formatDdlForDisplay(raw, 'duckdb');
+
+    expect(formatted).toContain('CREATE TABLE customers (');
+    expect(formatted).toContain('customer_id BIGINT,');
+    expect(formatted).toContain('PRIMARY KEY (customer_id)');
+    expect(formatted).toContain('\n');
+  });
+
+  it('returns original text when formatter cannot parse the statement', () => {
+    const raw = 'not valid ddl(';
+
+    expect(formatDdlForDisplay(raw, 'duckdb')).toBe(raw);
+  });
+});

frontend/src/utils/ddlFormat.ts

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+import { format } from 'sql-formatter';
+
+const resolveDdlFormatterLanguage = (dbType: string): string | null => {
+  const normalized = String(dbType || '').trim().toLowerCase();
+  switch (normalized) {
+    case 'duckdb':
+      return 'duckdb';
+    case 'sqlite':
+      return 'sqlite';
+    case 'postgres':
+    case 'postgresql':
+    case 'kingbase':
+    case 'highgo':
+    case 'opengauss':
+    case 'vastbase':
+      return 'postgresql';
+    case 'mariadb':
+      return 'mariadb';
+    case 'mysql':
+    case 'sphinx':
+      return 'mysql';
+    case 'sqlserver':
+      return 'transactsql';
+    case 'oracle':
+    case 'dameng':
+    case 'oceanbase':
+      return 'plsql';
+    case 'clickhouse':
+      return 'clickhouse';
+    default:
+      return 'sql';
+  }
+};
+
+export const formatDdlForDisplay = (ddlText: unknown, dbType: string): string => {
+  const raw = String(ddlText ?? '').trim();
+  if (!raw) {
+    return '';
+  }
+  const language = resolveDdlFormatterLanguage(dbType);
+  if (!language) {
+    return raw;
+  }
+  try {
+    return format(raw, {
+      language,
+      keywordCase: 'upper',
+      linesBetweenQueries: 1,
+    });
+  } catch {
+    return raw;
+  }
+};