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/core/models/openrouter.yaml

@@ -15,7 +15,7 @@ models:
 
   - id: deepseek/deepseek-v3.2
     display_name: DeepSeek V3.2
-    description: Open-weights reasoning model, very low cost (~$0.25 in / $0.38 out per 1M)
+    description: Open-weights reasoning model, very low cost (~$0.23 in / $0.34 out per 1M)
     context_window: 131072
     attachments: []
     supports_structured_output: true