✨ feat(data-grid): 支持无主键表安全编辑

- 定位策略：新增主键、唯一索引和 Oracle ROWID 三类安全行定位能力
- 查询编辑器：简单单表 SELECT 自动补充隐藏定位列，复杂结果保持只读
- 表预览：无主键表可通过唯一索引或 Oracle ROWID 安全编辑
- 提交流程：移除无主键整行 WHERE fallback，隐藏定位列不参与展示和写入
- 后端保护：Oracle、MySQL、PostgreSQL 更新删除必须恰好影响 1 行
- 测试覆盖：补充 QueryEditor、DataViewer、DataGrid 和 ApplyChanges 相关用例
Refs #419

internal/db/postgres_impl.go

@@ -408,6 +408,12 @@ JOIN pg_attribute a ON a.attrelid = t.oid AND a.attnum = x.attnum
 WHERE t.relkind IN ('r', 'p')
   AND t.relname = '%s'
   AND n.nspname = '%s'
+  AND ix.indisvalid
+  AND ix.indpred IS NULL
+  AND x.ordinality <= ix.indnkeyatts
+  AND NOT EXISTS (
+    SELECT 1 FROM unnest(ix.indkey) AS expr_key(attnum) WHERE expr_key.attnum <= 0
+  )
 ORDER BY i.relname, x.ordinality`, esc(table), esc(schema))
 
 	data, _, err := p.Query(query)
@@ -758,9 +764,13 @@ func (p *PostgresDB) ApplyChanges(tableName string, changes connection.ChangeSet
 			continue
 		}
 		query := fmt.Sprintf("DELETE FROM %s WHERE %s", qualifiedTable, strings.Join(wheres, " AND "))
-		if _, err := tx.Exec(query, args...); err != nil {
+		res, err := tx.Exec(query, args...)
+		if err != nil {
 			return fmt.Errorf("删除失败：%v", err)
 		}
+		if err := requireSingleRowAffected(res, "删除"); err != nil {
+			return err
+		}
 	}
 
 	// 2. Updates
@@ -791,9 +801,13 @@ func (p *PostgresDB) ApplyChanges(tableName string, changes connection.ChangeSet
 		}
 
 		query := fmt.Sprintf("UPDATE %s SET %s WHERE %s", qualifiedTable, strings.Join(sets, ", "), strings.Join(wheres, " AND "))
-		if _, err := tx.Exec(query, args...); err != nil {
+		res, err := tx.Exec(query, args...)
+		if err != nil {
 			return fmt.Errorf("更新失败：%v", err)
 		}
+		if err := requireSingleRowAffected(res, "更新"); err != nil {
+			return err
+		}
 	}
 
 	// 3. Inserts