Add sheet-music-server example

[jonathanhefner]

Demo MCP App showcasing ABC notation rendering and audio playback with:

• Server-side ABC notation validation
• Built-in audio player with play/pause and loop controls
• Sheet music visualization using abcjs library

🤖 Generated with Claude Code

Screenshots:

Twinkle, Twinkle	Playing on repeat

(Will push those screenshots to the gh-pages branch once this PR is merged.)

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/modelcontextprotocol/ext-apps/@modelcontextprotocol/ext-apps@196

commit: 012fb32

[antonpk1]

very cool! one thing - the audio playback doesn't work because the soundfonts from paulrosen.github.io are blocked by CSP.

fix: add connectDomains to the resource response in server.ts:

return{contents: [{uri: resourceUri,mimeType: RESOURCE_MIME_TYPE,text: html,_meta: {ui: {csp: {// Allow loading soundfonts from paulrosen.github.io for audio playbackconnectDomains: ["https://paulrosen.github.io"],},},},},],};

[jonathanhefner]

@antonpk1 Thank you!! I applied your fix.