feat: zai windows render absolute reset time

[rz1989s]

Summary

zai quota windows now append the absolute local reset time after the countdown — (pace · countdown · HH:MM) same-day, (pace · countdown · Mon DD HH:MM) cross-day — so 23:30 and Sep 12 04:09 read at a glance instead of requiring mental math from 3h 19m.

• formatResetAbs(epochMs, now) — absolute local wall-clock: HH:MM same-day, Mon DD HH:MM cross-day, now if the epoch is already past
• zaiLine window fragments gain the absolute as a third dim separator segment; removed lines (no epoch) render unchanged
• README/header/hero SVG synced with the absolute-time format; hero canvas widened 866→980 to fit the longer 7DAY fragment without clipping

Spec: docs/superpowers/specs/2026-09-09-zai-reset-time-design.md
Plan: docs/superpowers/plans/2026-09-09-zai-reset-time.md

Verification

• pnpm typecheck clean; pnpm test:run 20/20 pass
• Live smoke against the real zai API (2026-09-09), rendering the real zaiLine:

 󰚯 zai 5hrs 9%/34% (1h 15m under · 3h 19m · 23:30) · 7DAY 76%/67% (15h 7m over · 2d 7h · Sep 12 04:09)

Anchors match the spec: 5HRS resets 23:30 Asia/Jakarta today; 7DAY resets Sep 12 04:09 Asia/Jakarta.