chore: remove metadata field and jid attribute

These weren't used.

src/control_backend/core/agent_system.py

@@ -1,8 +1,7 @@
 import asyncio
 import logging
 from abc import ABC, abstractmethod
-from dataclasses import dataclass, field
-from typing import Any
+from dataclasses import dataclass
 
 # Central directory to resolve agent names to instances
 _agent_directory: dict[str, "BaseAgent"] = {}
@@ -14,7 +13,6 @@ class InternalMessage:
     sender: str
     body: str
     thread: str | None = None
-    metadata: dict[str, Any] = field(default_factory=dict)
 
 
 class AgentDirectory:
@@ -32,7 +30,6 @@ class BaseAgent(ABC):
 
     def __init__(self, name: str):
         self.name = name
-        self.jid = name  # present for backwards compatibility
         self.inbox: asyncio.Queue[InternalMessage] = asyncio.Queue()
         self._tasks: set[asyncio.Task] = set()
         self._running = False
@@ -83,5 +80,3 @@ class BaseAgent(ABC):
         task = asyncio.create_task(coro)
         self._tasks.add(task)
         task.add_done_callback(self._tasks.discard)
-
-        # await asyncio.sleep(1)