feat(quota): display weekly reset countdown

[dvd233]

Summary

Fixes #248.

• Show the weekly quota reset countdown in the quota table header, aligned with the existing reset column.
• Reuse the API's weekly_start_time, weekly_end_time, and weekly_remains_time fields.
• Render long weekly durations as days and hours while preserving existing per-model reset formatting.

Test Plan

• bun test test/output/quota-table.test.ts — 11 passed
• bun run typecheck — passed
• bun run lint — 0 errors; one pre-existing warning in test/sdk/speech.test.ts
• bun run build — passed
• bun test — 563 passed, 12 existing Windows-environment failures involving permissions, symlinks, proxy state, and powershell.exe; the changed quota suite passes

Notes

PR #255 added seconds for sub-minute reset durations and explicitly stated that the weekly header proposed in #248 was not included. This PR implements that remaining UI request without changing API or JSON output.

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