🐛 fix(oceanbase): 修复 OceanBase 协议模式识别与缓存隔离

- 支持 MySQL/Oracle 租户协议在前后端统一解析
- 拒绝 Native 协议并避免误回退为 MySQL
- 修复 Oracle 模式下元数据、DDL、SQL 方言识别
- 修复连接缓存键与实际协议解析优先级不一致问题
- 补充前后端协议解析与缓存隔离回归测试

frontend/src/utils/dataSourceCapabilities.test.ts

@@ -40,4 +40,16 @@ describe('dataSourceCapabilities', () => {
       supportsApproximateTableCount: true,
     });
   });
+
+  it('treats custom OceanBase Oracle driver as Oracle capabilities', () => {
+    expect(getDataSourceCapabilities({
+      type: 'custom',
+      driver: 'oceanbase',
+      oceanBaseProtocol: 'oracle',
+    })).toMatchObject({
+      type: 'oracle',
+      preferManualTotalCount: true,
+      supportsApproximateTableCount: true,
+    });
+  });
 });