[FEATURE] Option to suppress or reduce frequency of the "Now you're using usage credits" banner

### Preflight Checklist

- [x] I have searched [existing requests](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20label%3Aenhancement) and this feature hasn't been requested yet
- [x] This is a single feature request (not multiple features)

### Problem Statement

**Description:**

When a subscription user exhausts their included plan usage and rolls over into extra usage credits, Claude Code shows a persistent "Now you're using usage credits" message at the bottom of the terminal UI. There is currently no way to dismiss it, and no setting or environment variable to disable it.

**The problem:**

→ The message is persistent for the entire time you're drawing on usage credits, which for heavy users can be most of the working day. After the first occurrence it carries no new information, but it permanently occupies a line of terminal real estate in every session.

→ For users who have deliberately enabled usage credits and are fully aware they're
paying per-token, the constant reminder is noise rather than signal.

→ Other Claude Code notices are configurable (e.g. spinnerTipsEnabled, terminalProgressBarEnabled), but this one has no corresponding setting.

_Environment: Claude Code CLI on macOS, subscription plan (Max) with extra usage credits enabled._

### Proposed Solution

**Proposed solutions (either would help):**

1. Rate-limit the notice — show it once per day (or once per usage window) when the transition into usage credits happens, then hide it, instead of displaying it persistently.

2. Make it configurable — add a setting (e.g. usageCreditsNoticeEnabled in settings.json) or an environment variable so users who opted into pay-as-you-go can turn the banner off entirely.

A one-time, dismissible notification at the moment of transition is genuinely useful; a permanent banner is not. Related: #51669 was closed as "not planned," but that asked for more persistent usage display — this request is the opposite: less.

### Alternative Solutions

_No response_

### Priority

Low - Nice to have

### Feature Category

CLI commands and flags

### Use Case Example

_No response_

### Additional Context

_No response_

Start by tracing the terminal UI path that renders the persistent usage-credits banner and compare it with the existing spinnerTipsEnabled and terminalProgressBarEnabled settings. Review the proposed settings.json option and environment-variable alternative, then determine whether rate-limiting or dismissal is the intended behavior; done means the banner is no longer persistent while the transition notice remains useful.

Rédigé par le modèle d'indexation à partir du texte de l'issue.