🐛 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/types.ts

@@ -299,7 +299,7 @@ export interface ConnectionConfig {
   redisDB?: number; // Redis database index (0-15)
   uri?: string; // Connection URI for copy/paste
   clickHouseProtocol?: "auto" | "http" | "native"; // ClickHouse connection protocol override
-  oceanBaseProtocol?: "mysql" | "oracle"; // OceanBase tenant protocol
+  oceanBaseProtocol?: "mysql" | "oracle"; // OceanBase tenant compatibility protocol
   hosts?: string[]; // Multi-host addresses: host:port
   topology?: "single" | "replica" | "cluster";
   mysqlReplicaUser?: string;