Summary

Implements the Bounty Countdown Timer component for bounty cards and detail pages with real-time updates and visual urgency indicators.

What's New

• BountyCountdownTimer — standalone React component with live countdown (d/h/m/s)
• Compact & full modes — compact for bounty cards, full for detail page sidebar
• Visual urgency states:
  • 🟡 Amber warning when < 24 hours remain
  • 🔴 Red urgent + pulsing icon when < 1 hour remain
  • ⚫ Expired state when deadline passes
• Real-time updates — refreshes every second via setInterval, auto-stops when expired
• lib/utils.ts — adds missing shared utilities (timeLeft, timeAgo, formatCurrency, LANG_COLORS)

Files Changed

• frontend/src/components/bounty/BountyCountdownTimer.tsx — new component
• frontend/src/components/bounty/BountyCard.tsx — uses BountyCountdownTimer (compact)
• frontend/src/components/bounty/BountyDetail.tsx — uses BountyCountdownTimer (full)
• frontend/src/lib/utils.ts — new shared utilities

Testing

• Component handles expired deadlines gracefully
• Timer auto-stops via clearInterval when expired to prevent memory leaks
• Uses React best practices (useEffect cleanup, useState initializer)