🐛 fix(kingbase): 统一金仓标识符引用策略

- 标识符处理：下沉 Kingbase 引用逻辑，普通小写 schema/table 不再强制双引号包裹
- 表操作修复：修复截断、清空、导入、导出等路径生成异常双引号 SQL
- 同步链路修复：统一数据同步、预览、迁移建表中的 Kingbase schema.table 拼接规则
- 自定义驱动兼容：补齐 kingbase8/kingbasees/kingbasev8 别名归一与写入路径处理
- 回归覆盖：新增 ldf_server.andon_events、转义引号、保留字和大小写标识符测试

internal/app/sql_sanitize_test.go

@@ -11,6 +11,15 @@ func TestSanitizeSQLForPgLike_FixesBrokenDoubleDoubleQuotes(t *testing.T) {
 	}
 }
 
+func TestSanitizeSQLForPgLike_KingbaseAliasFixesBrokenDoubleDoubleQuotes(t *testing.T) {
+	in := `SELECT * FROM ""ldf_server"".""t_user"" LIMIT 1`
+	out := sanitizeSQLForPgLike("kingbase8", in)
+	want := `SELECT * FROM "ldf_server"."t_user" LIMIT 1`
+	if out != want {
+		t.Fatalf("unexpected sanitize output:\nIN:   %s\nOUT:  %s\nWANT: %s", in, out, want)
+	}
+}
+
 func TestSanitizeSQLForPgLike_FixesBrokenDoubleDoubleQuotes_WithExtraQuotes(t *testing.T) {
 	in := `SELECT * FROM ""ldf_server""".""t_user"" LIMIT 1`
 	out := sanitizeSQLForPgLike("kingbase", in)