GitLab

- Simplify OpenAI rendering: always fetch /usage, prefer fetched data over
  codex snapshot (snapshot serves as loading placeholder only)
- Remove dead code: preferFetchedOpenAIUsage, isOpenAICodexSnapshotStale,
  and unreachable template branch
- Add today-stats support for key accounts (req/tokens/A/U badges)
- Use formatCompactNumber for consistent number formatting
- Add A/U badge titles for clarity
- Filter zero-value window stats in UsageProgressBar to avoid empty badges
- Update tests to match new fetched-data-first behavior

Replace process-memory sync.Map + per-model runtime state with a single
"AICredits" key in model_rate_limits, making credits exhaustion fully
isomorphic with model-level rate limiting.

Scheduler: rate-limited accounts with overages enabled + credits available
are now scheduled instead of excluded.

Forwarding: when model is rate-limited + credits available, inject credits
proactively without waiting for a 429 round trip.

Storage: credits exhaustion stored as model_rate_limits["AICredits"] with
5h duration, reusing SetModelRateLimit/isRateLimitActiveForKey.

Frontend: show credits_active (yellow ⚡) when model rate-limited but
credits available, credits_exhausted (red) when AICredits key active.

Tests: add unit tests for shouldMarkCreditsExhausted, injectEnabledCreditTypes,
clearCreditsExhausted, and update existing overages tests.

Extract applyInterceptWarmup utility to unify all credential building
call sites:
- Fix upstream account creation missing intercept_warmup_requests write
- Fix apikey edit mode missing else-branch to clear the setting
- Add backend unit test for IsInterceptWarmupEnabled
- Add frontend unit test for credentialsBuilder