feat: Enhance plugin runtime with new component registry and workflow executor

- Introduced `ComponentRegistry` for managing plugin components with support for registration, enabling/disabling, and querying by type and plugin.
- Added `EventDispatcher` to handle event distribution to registered event handlers, supporting both blocking and non-blocking execution.
- Implemented `WorkflowExecutor` to manage a linear workflow execution across multiple stages, including command routing and error handling.
- Created `ManifestValidator` for validating plugin manifests against required fields and version compatibility.
- Updated `RPCClient` to use `MsgPackCodec` for message encoding.
- Enhanced `PluginRunner` to support lifecycle hooks for plugins, including `on_load` and `on_unload`.
- Added sys.path isolation to restrict plugin access to only necessary directories.

src/plugin_runtime/runner/rpc_client.py

@@ -14,7 +14,7 @@ import asyncio
 import logging
 import uuid
 
-from src.plugin_runtime.protocol.codec import Codec, create_codec
+from src.plugin_runtime.protocol.codec import Codec, MsgPackCodec
 from src.plugin_runtime.protocol.envelope import (
     PROTOCOL_VERSION,
     Envelope,
@@ -49,7 +49,7 @@ class RPCClient:
     ):
         self._host_address = host_address
         self._session_token = session_token
-        self._codec = codec or create_codec()
+        self._codec = codec or MsgPackCodec()
 
         self._id_gen = RequestIdGenerator()
         self._connection: Connection | None = None