feat: add Peak Hours widget with color-coded countdown

[elhoim]

Summary

• Adds a new Peak Hours widget that shows Anthropic's peak hours status (weekdays 5am-11am PT) with a countdown timer
• Displays red with ⚠ warning sign during peak hours, green with time-until-next-peak outside
• Uses Intl.DateTimeFormat with America/Los_Angeles timezone for automatic DST handling
• Generalizes preserveColors in the renderer to work for any widget type (not just custom-command)

Widget details

• Type slug: peak-hours | Category: Usage
• Supports compact mode (s keybind) and raw value mode
• Widget manages its own ANSI color codes (red/green) — getDefaultColor() returns '' to prevent renderer from overriding
• Reuses existing formatUsageDuration, formatRawOrLabeledValue, isUsageCompact, and applyColors utilities
• Intl.DateTimeFormat formatter is cached at module level for performance

Files changed

• src/widgets/PeakHours.ts — New widget (165 lines)
• src/widgets/__tests__/PeakHours.test.ts — 34 tests covering timezone logic, rendering, colors, editor actions
• src/utils/renderer.ts — Generalize preserveColors check (4 locations)
• src/utils/widget-manifest.ts — Register widget
• src/widgets/index.ts — Export widget

Test plan

• bun test — all 631 tests pass (including 34 new)
• bun run lint — zero errors
• Manual test with piped input confirms green "Peak in: Xhr Xm" output outside peak hours
• Manual test confirms red "⚠ Peak: Xhr Xm" during peak hours (via withFixedTime in tests)

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