fix(quotas): address review: resume claims, agent bucket rule, UI races

- A tool continuation refused for usage now releases the resume claim it
  took; before, retries got a 409 until the stale claim was reverted.
- Agent traffic is any row with an agent key or an agent id, so keyless
  agents and workflow nodes count toward the agent bucket, not direct.
- The user quota modal discards responses for a previously opened user.
- The usage meter shows every limited bucket, not only 'all'.
- Restore the class separator on the analytics stat card that a formatter
  run removed, and align the OpenRouter DeepSeek description with its rates.

docsgpt/api/answer/routes/stream.py

@@ -115,9 +115,9 @@ class StreamResource(Resource, BaseAnswerResource):
                         status=401,
                         mimetype="text/event-stream",
                     )
-                if error := self.check_usage(
-                processor.agent_config, processor.decoded_token
-            ):
+                if error := self.check_usage_on_resume(
+                    processor, data["conversation_id"]
+                ):
                     return error
                 return Response(
                     with_sse_keepalive(