feat: add optional per-account Smart refresh

[ElliotDrel]

Fixed refresh intervals either leave active usage stale or keep polling idle accounts. This adds an optional Smart choice under Settings → Auto refresh, using the existing preference and keeping the default at 15 minutes.

• A quota change starts five minutes of one-minute checks. Unchanged successful results then step through 2, 5, 10 and 15 minutes; any further change returns to one minute.
• Each account has its own schedule, calculated when its result arrives. One timer wakes the next due accounts, and in-flight checks are not repeated. When every account is in flight, the footer shows “Refreshing…” rather than “Paused”.
• Only raw progress values and limits count as activity. Countdown text, status messages and local history charts do not reset the schedule. Failed/stale results use a separate capped 2/5/10/15-minute backoff; the existing native HTTP rate-limit gate remains in place.
• Opening the panel refreshes data at least a minute old, without bypassing error backoff. With no other signal, resumed usage can take up to 15 minutes to be detected.
• Smart polls reuse successful local token-history results for 15 minutes, keyed by account and query options. Manual refreshes and fixed intervals still scan fresh history and replace the cache. Quota requests remain live.
• No new dependencies, file watchers or burn-rate prediction. Includes all 11 UI translations and regression tests for transitions, independent/slow accounts, failures, cancellation, focus refresh, settings persistence, IPC opt-in and local-history cache behavior.

Validation:

• Production frontend build and TypeScript check passed.
• Full frontend/provider suite passed: 74 files, 1,294 tests (node node_modules/vitest/vitest.mjs run --pool=threads --maxWorkers=2). The initial wrapper stalled starting workers; running Vitest directly completed successfully.
• Windows verification passed the frontend build, cargo test --locked --lib (212 passed, 1 ignored), and cargo build --locked --bins at 9794dc1. Native source is unchanged since that run; the final footer-only correction passed a fresh frontend build and full suite. The fork-only verification workflow is not part of this PR.
• Screenshots omitted at the requester's direction. This PR starts from upstream main and contains no taskbar-placement changes.

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-15T20:52:33.838556Z	9a2cda3	Draft marked ready

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