feat(agent-chat): complete core workflow and strengthen auth rate limiting

backend/src/v1/agent_chat/dependencies.py

@@ -0,0 +1,18 @@
+from __future__ import annotations
+
+from typing import Annotated
+
+from fastapi import Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from core.auth.models import CurrentUser
+from core.db import get_db
+from v1.agent_chat.service import AgentChatService
+from v1.profile.dependencies import get_current_user
+
+
+def get_agent_chat_service(
+    session: Annotated[AsyncSession, Depends(get_db)],
+    user: Annotated[CurrentUser, Depends(get_current_user)],
+) -> AgentChatService:
+    return AgentChatService(session=session, current_user=user)