Add debug logging to /v1/agent/chat route handler

Log agent_type, full models payload and selected model on every request
to diagnose endpoint routing and empty-endpoint issues.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server.py

@@ -558,6 +558,12 @@ async def agent_chat(req: ChatRequest, authorization: str = Header(default="")):
     valid_poses = agent.poses if agent.poses else ["neutral"]
     model       = select_model(req.models)
 
+    log.info(
+        f"[route] agent={agent.name!r} agent_type={agent.agent_type!r} "
+        f"models_payload={req.models} "
+        f"selected_model={model}"
+    )
+
     # ── Route: Hermes Agent ───────────────────────────────────────────────────
     if agent.agent_type == "hermes":
         if not model or not model.endpoint: