[FEATURE]: Show provider quota beside prompt metrics #24960

Describe the enhancement you want to request

Show provider quota in the TUI prompt metrics row, next to the existing context/cost metrics.

Narrow scope for this issue:

• start with exact Codex quota from the OAuth account
• expose a provider-quota shape that can later hold Copilot/other provider quotas
• keep the UI compact and non-blocking

Related: #19190 asked for broader quota surfaces. This is the smaller prompt-metrics version validated in the standalone plugin.

Benefits

• Users can see quota before submitting prompts.
• The signal lives where context usage already appears.
• A provider-quota shape leaves room for future providers without hardcoding the prompt row to Codex only.

Prototype screenshots: https://github.com/50sotero/opencode-usage-quota#screenshots