Responsive desktop and mobile player redesign

[cjocollin]

Summary

• rebuild the MP5 shell to match the approved desktop/mobile concept
• add the responsive player workspace, track inspector, compact queue, persistent transport, and mobile bottom navigation
• preserve file ingest, playback, seek, volume, queue, VISU, album, converter, library, demo, About, and Settings behavior
• add real MP5 waveform artwork, self-hosted DM Sans, and Phosphor icons
• refine the visual system to the approved Studio Neutral palette while preserving violet/cyan badge semantics
• stabilize the Android mobile bottom stack across tab switches: the persistent transport remains available, the navigation uses a constant outer height with a reserved safe-area region, and tab changes no longer animate the visual viewport
• expand the mobile regression check to repeat Player ↔ Converter transitions with touch/mobile emulation

Safety

This remains an isolated draft PR. Nothing in this PR has been merged or deployed to production.

Verification

• TypeScript and production Vite build — passed
• complete unit suite — 569 passed, 2 intentionally skipped
• corrective diff review — no P1/P2 findings
• Vercel branch preview — ready
• focused mobile geometry regression — added; full GitHub E2E run pending
• reported Android Custom Tab — confirmation pending on the user's device

[vercel]

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Project	Deployment	Actions	Updated (UTC)
mp5-audio	Ready	Preview, Comment	Jul 18, 2026 6:32am