Confirm usage-limit resets before redemption (#33845)

## Why

Selecting a usage-limit reset from the picker immediately started redemption,
leaving no opportunity to verify the choice.

## What changed

- Open a separate confirmation popup before redeeming a selected reset, with
  `No, go back` selected by default.
- Show backend-provided reset titles and descriptions in the picker and
  confirmation, with generic fallback copy when those details are absent.
- Ignore duplicate or stale confirmation and redemption events, while retaining
  the idempotency key needed to retry a failed redemption.

## Testing

- Added coverage for confirmation, cancellation, backend copy, duplicate and
  stale events, successful redemption, and retry behavior.

GitOrigin-RevId: 828945f99f06e8c73941fd864e4aa9ac52729f98

codex-rs/tui/src/chatwidget.rs

@@ -563,6 +563,8 @@ pub(crate) struct ChatWidget {
     completed_token_activity_output: Option<history_cell::CompositeHistoryCell>,
     next_token_activity_request_id: u64,
     pending_rate_limit_reset_request_id: Option<u64>,
+    pending_rate_limit_reset_idempotency_key: Option<String>,
+    rate_limit_reset_picker_request_id: Option<u64>,
     pending_rate_limit_reset_hint_request_id: Option<u64>,
     pending_usage_menu_rate_limit_request_id: Option<u64>,
     pending_rate_limit_reset_hint: Option<PlainHistoryCell>,