Publish a manifest of the example scores, and fill in their project information

[jcelerier]

Lets the application list what this site ships without hardcoding anything: a
Jekyll generator walks assets/scores/**/*.{score,zip}, reads each document's
project information, and publishes assets/scores/index.json plus a PNG of the
thumbnail each document stores.

• every score under assets/ is indexed, not only the ones with a doc page: 83 entries
• each one has a name, a description, a section/group/category, its download size,
  the page that documents it when there is one, and the platforms it runs on
• script/examples/metadata.rb is the harness that filled all of this in and can
  check it again (status, prepare, describe, capture, sync, relativize,
  platforms)
• the archives were repacked so they carry their own media
• the four examples that need NDI, raw evdev or a Windows-only plug-in are marked
  as not running on the web

Consumed by ossia/score#2293, which lists these in the start screen's Examples tab.

Carries the csf docs work this branch was written on top of.

🤖 Generated with Claude Code

https://claude.ai/code/session_01SCvayD61okH7PATstw4whi