fix(ui, cli): humanize provider retry delay (3401)

[yunaremaia]

Fixes #3401.

When a provider returns a long Retry-After (~13565s for a 5h quota reset), the retry banner renders Retrying in 13565s / 13565 秒后重试 — illegible. Related to #3393 (countdown ticking).

What changed

• packages/ui/src/conversation-copy.ts — new formatRetryDelay(seconds, locale): 13565 → 3h 46m 5s (en) / 3小时 46分 5秒 (zh), 1s granularity. Wired into both zh/en providerRetryScheduled catalog entries.
• packages/cli/src/pi-transcript.ts — new formatRetryDuration(delayMs) for the TUI activity strip; same humanized output (en).

Granularity stays at one second so the banner visibly ticks (minute-granularity would reintroduce the frozen look from #3393).

Verification

• formatRetryDelay spot-checked locally (13565→3h 46m 5s, 90061→1d 1h 1m 1s, edge: 0.2→1s).
• No registry workaround; change is compile-only (no new deps).
• Full local build/test not run — relies on @xterm/xterm custom registry (ms-feed-2.pkgs.visualstudio.com); CI is the verification layer.

Closes #3401.
Related: #3393.

[Astro-Han]

Reviewed exact head 742bbc9. Coverage: UI zh/en duration formatting over seconds/minutes/hours/days and fractional-second rounding; CLI millisecond formatting and narrow-line fitting; provider-retry event bounds/countdown flow; confirmation that Runtime retry-after/backoff calculation, sleep, attempts, and protocol transport are unchanged. Exclusions: real provider Retry-After traffic and interactive terminal/renderer visual inspection. Local UI→CLI builds passed and 228 focused UI/CLI tests are green; hosted exact-head test is green. No P0–P3 findings. The branch is 24 commits behind main and currently conflicts only in packages/ui/src/conversation-copy.ts; rebase should preserve current main’s newer copy entries plus this PR’s formatter/wiring.