fix(ui): humanize provider retry delay in the banner copy

[me2seeks]

Fixes #3401.

Problem

With a long provider Retry-After (subscription quota window reset, e.g. kimi-k3 / OpenCode Go 5h quota), the desktop retry banner renders a raw five-digit second count — 13565 秒后重试（2/10） — illegible and visually indistinguishable from a hang. The TUI strip already humanizes the same wait as 4h 28m 3s (#3393).

Fix

Format providerRetryScheduled in d/h/m/s units per locale:

• zh: 4小时 28分 3秒后重试（2/10）
• en: Retrying in 4h 28m 3s (2/10)

One-second granularity is kept so the banner visibly ticks every second — the goal chip's minute-granularity ladder would reintroduce the frozen look between minute boundaries. Short delays keep the familiar seconds-only form (45秒后重试 / Retrying in 45s).

Tests

New conversation-copy.test.ts pins both locales across second/minute/hour/day scales. Full ui suite (184) passes; biome lint/format clean.

Note: independent of #3400 (countdown ticking); either merge order works.

[jackwener]

Automated review of exact head ef7097b50a91c7dc5284f00180db0ffe15a95fa4.

I confirmed the current main copy still renders provider waits as raw seconds, and the patch fixes that at the presentation boundary without changing retry policy. The d/h/m/s formatter is bounded, locale-specific, and the focused UI build plus new locale test passed locally (1/1). I found no P0-P2 correctness issue.

Merge readiness: not ready yet. This head has no hosted check result and still requires an independent human review; both gates should be present on this exact head before merge.