## Why
Supported clients currently receive only a reset-credit count from
`account/rateLimits/read`. The redemption UI and other app-server
clients need each available credit's expiry and ID so they can explain
what will expire and consume the credit a user selected. This
information belongs on the existing rate-limit read surface rather than
a second app-server list RPC that clients would need to coordinate.
## What changed
- extend `rateLimitResetCredits` on `account/rateLimits/read` with
nullable `credits` detail rows
- fetch usage and reset-credit details concurrently; if the detail
request fails, times out, or cannot be parsed, preserve the usage
response and return `credits: null`
- expose each credit's ID, reset type, status, grant time, expiry time,
title, and description
- add an optional nullable `creditId` to
`account/rateLimitResetCredit/consume`; omitting it preserves the
existing automatic-selection behavior
- forward a selected credit ID to the Codex backend and update the
app-server documentation and generated schemas
The TUI consumer is stacked in #30488.
## Validation
- `just test -p codex-app-server-protocol` (251 passed)
- `just test -p codex-backend-client` (16 passed)
- `just test -p codex-app-server rate_limit` (18 passed)
Part of #29618.
jay
58ec528315