🐛 fix(duckdb): 修复唯一索引识别与多库对象解析

- 合并 DuckDB 约束与索引元数据，恢复唯一索引表的可编辑判定
- 修复 attach 多库场景下 catalog/schema/table 定位混乱问题
- 统一前后端 qualified name 解析，支持带点和带引号对象名
- 补充 DuckDB 元数据与编辑链路回归测试

frontend/src/utils/sql.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest';
 
-import { buildOrderBySQL, buildPaginatedSelectSQL, reverseOrderBySQL } from './sql';
+import { buildOrderBySQL, buildPaginatedSelectSQL, quoteQualifiedIdent, reverseOrderBySQL } from './sql';
 
 describe('buildOrderBySQL', () => {
   it('does not add fallback ORDER BY for DuckDB without explicit sort', () => {
@@ -52,3 +52,15 @@ describe('reverseOrderBySQL', () => {
       .toBe(' ORDER BY COALESCE([a], [b]) DESC, [id] ASC');
   });
 });
+
+describe('quoteQualifiedIdent', () => {
+  it('does not split dots inside quoted DuckDB identifiers', () => {
+    expect(quoteQualifiedIdent('duckdb', '"daily.events"."2026.06"'))
+      .toBe('"daily.events"."2026.06"');
+  });
+
+  it('preserves three-part DuckDB names with quoted dots', () => {
+    expect(quoteQualifiedIdent('duckdb', '"analytics.catalog"."main.schema"."daily.events"'))
+      .toBe('"analytics.catalog"."main.schema"."daily.events"');
+  });
+});