Feature request: Show additional usage budget in the app

Feature request: Show additional usage budget in the app

When my included AI token allowance is exhausted and usage switches to my **Additional usage** budget, there’s no in-app way to see how much I’ve used, how much remains, or what my limit is. I have to leave the app and visit the website to find this information, which is inconvenient and makes it difficult to monitor spending while working.

Please add an in-app usage view that shows:

- Additional usage consumed
- Remaining budget or current limit
- Billing period or reset date
- A link to manage or adjust the budget

This would make usage and spending much more transparent and provide a smoother experience for users who rely on additional usage.

---
| Field | Value |
| --- | --- |
| App version | 1.1.12 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 7 |

Start at the app's /chat experience and trace how included AI token usage and the existing website billing link are surfaced. Determine where additional usage data, limits, reset dates, and budget-management links can be obtained and displayed. Done means the in-app view shows consumed usage, remaining or maximum budget, the billing period or reset date, and a management link.

索引モデルが issue の本文から書いたものです。