feat(mearrow): add responsive mobile navigation

[moony01]

Summary

• Add responsive mobile header and fixed bottom navigation
• Add mobile tabs: 홈, 투표, 업로드, 뉴스, 프로필
• Move 명예의 전당 and 오디션 into the mobile header drawer
• Preserve Supabase/Tailscale data loading and reserve feed space for the bottom bar
• Open the feed composer from /my?compose=1

Verification

• pnpm exec tsc --noEmit
• pnpm lint
• pnpm vitest run
• pnpm build
• Mobile browser verification at 320px and 390px
• Desktop regression verification at 1440px
• Tailscale routes and Supabase REST requests verified

Deployment

• Merge to main should trigger the MEARROW Workers pull-request validation, then the main push deployment workflow.