Add browser MIDI mapping controls and stop markers

[Sportinger]

Summary

• add browser MIDI runtime, settings tab, mapping panel, and project persistence for transport plus marker bindings
• add editable MIDI mappings, panel-side trigger previews, and marker context menu learn/binding actions
• add stop markers plus marker actions for jump, play-from-marker, and jump-and-stop

Verification

• npm run build
• npm run lint
• npm run test

Preview

• https://midi.masterselects.pages.dev
• https://2045ba30.masterselects.pages.dev

[cloudflare-workers-and-pages]

Deploying masterselects with    Cloudflare Pages

Latest commit:	eefcc19
Status:	✅  Deploy successful!
Preview URL:	https://615aaa72.masterselects.pages.dev
Branch Preview URL:	https://midi.masterselects.pages.dev

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