🐛 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/sqlDialect.test.ts

@@ -23,6 +23,7 @@ describe('sqlDialect', () => {
     expect(resolveSqlDialect('custom', 'mariadb')).toBe('mariadb');
     expect(resolveSqlDialect('custom', 'open_gauss')).toBe('opengauss');
     expect(resolveSqlDialect('OceanBase', '', { oceanBaseProtocol: 'oracle' })).toBe('oracle');
+    expect(resolveSqlDialect('custom', 'oceanbase', { oceanBaseProtocol: 'oracle' })).toBe('oracle');
     expect(isMysqlFamilyDialect('mariadb')).toBe(true);
     expect(isMysqlFamilyDialect('oceanbase')).toBe(true);
     expect(isMysqlFamilyDialect('oracle')).toBe(false);