🐛 fix(metadata): 修复 Oracle 字段元数据显示缺失

- Oracle 元数据查询为字段名、类型、默认值、注释等列补齐稳定别名

- 新增字段定义归一化工具，兼容 name/Name/COLUMN_NAME 等返回形态

- 修复 DataGrid、DataViewer、QueryEditor、TableDesigner 对字段元数据的读取

- 补充 Oracle 字段注释、表头元数据和主键定位回归测试

frontend/src/utils/columnDefinition.test.ts

@@ -0,0 +1,31 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  getColumnDefinitionComment,
+  getColumnDefinitionKey,
+  getColumnDefinitionName,
+  getColumnDefinitionType,
+  normalizeColumnDefinition,
+} from './columnDefinition';
+
+describe('columnDefinition metadata normalization', () => {
+  it('reads Go/Wails style column metadata fields', () => {
+    const column = { Name: 'UPDATED_AT', Type: 'TIMESTAMP', Key: 'PRI', Comment: '更新时间' };
+
+    expect(getColumnDefinitionName(column)).toBe('UPDATED_AT');
+    expect(getColumnDefinitionType(column)).toBe('TIMESTAMP');
+    expect(getColumnDefinitionKey(column)).toBe('PRI');
+    expect(getColumnDefinitionComment(column)).toBe('更新时间');
+  });
+
+  it('reads Oracle dictionary style column metadata aliases', () => {
+    const column = { COLUMN_NAME: 'UPDATED_AT', DATA_TYPE: 'TIMESTAMP', COLUMN_KEY: 'PRI', COMMENTS: '更新时间' };
+
+    expect(normalizeColumnDefinition(column)).toMatchObject({
+      name: 'UPDATED_AT',
+      type: 'TIMESTAMP',
+      key: 'PRI',
+      comment: '更新时间',
+    });
+  });
+});