Refactor ruapc into modular crates with trait-based transport abstractions

[Copilot]

Splits monolithic ruapc into independent crates with trait-based socket/socket-pool abstractions. Enables per-transport versioning and dependency selection.

New Crates

• ruapc-core — Error, Message, Payload, MsgMeta, SendMsg
• ruapc-async — TaskSupervisor, TaskSupervisorGuard
• ruapc-transport — RuapcSocket, RuapcSocketPool, MessageHandler traits
• ruapc-tcp — TCP transport (TcpSocket, TcpSocketPool)
• ruapc-ws — WebSocket transport (WebSocket, WebSocketPool)
• ruapc-http — HTTP transport with RapiDoc serving (HttpSocket, HttpSocketPool)

Architecture

ruapc-core        ← fundamental types
ruapc-async       ← async utilities (tokio only)
ruapc-transport   ← trait definitions
    ↑
ruapc-{tcp,ws,http}  ← transport implementations
    ↑
ruapc             ← RPC framework (Router, Context, Client, Server)

Key Traits

#[async_trait]
pub trait RuapcSocket: Send + Sync {
    async fn send(&self, meta: MsgMeta, payload: Bytes) -> Result<()>;
}

#[async_trait]
pub trait RuapcSocketPool: Send + Sync {
    fn socket_type(&self) -> SocketType;
    async fn get_socket(&self, addr: &str) -> Result<Arc<dyn RuapcSocket>>;
    async fn start_server(&self, addr: &str, handler: Arc<dyn MessageHandler>) -> Result<()>;
}

Backward Compatibility

Main ruapc crate re-exports all transport crates—existing code works unchanged.

Original prompt

对 ruapc 核心代码进行一次完整重构，合理地拆分为数个独立的 crate，使其架构更清晰。单元测试环境的配置可以参考 workflows 中的 CI 文件。

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.