feat(examples): download example as a standalone Vite project

[kpal81xd]

Summary

Adds a Download button to the examples-browser code panel toolbar (next to the refresh/GitHub icons) that exports the currently-viewed example as a runnable, self-contained Vite project — generated entirely in-browser, no server or hosting changes.

The zip is produced client-side with fflate (already bundled). It captures the live Monaco buffers, so any edits the user made in the code panel are included.

Preview

What's in the generated project

<category>-<example>/
  package.json      vite.config.mjs    index.html
  README.md
  CREDITS.md        (asset attribution from @credit — only when the example has credits)
  src/
    example.mjs       (@config stripped, imports rewritten)
    context.mjs       (local shim for `examples/context`)
    data.json         (captured control values)
    main.mjs          (imports the example, then replays data.json)
    <shaders / text>  (shipped verbatim, raw imports get `?raw`)
  public/
    assets/… scripts/…        (referenced assets, fetched from /static)
    assets/spine/license.txt  (folder licenses whose terms require shipping the file)

• Imports rewritten — examples/context → ./context.mjs; non-published examples/assets/scripts/** modules are vendored (and their imports recursed); playcanvas / playcanvas/scripts/** left as npm specifiers.
• Control state — the example's current control values are captured into src/data.json and replayed after the example initialises, mirroring the browser's applyControlState (so values that the example seeds itself aren't clobbered).
• Assets — source is scanned for ./assets/ & ./scripts/ URLs, fetched from the live /static/…, and shipped under public/ so they resolve unchanged. Dynamic/remote URLs that can't be bundled are noted in the generated README.
• Attribution — author-written @credit blocks (title / author / source / license) are written to a dedicated CREDITS.md, so asset attribution survives in the download. This covers remote / CDN assets (e.g. gaussian-splatting scenes) that ship no local license file. The credits come from the same parse the in-app credits overlay uses (surfaced via the example snapshot), so there's no guesswork or duplicate parsing. Folder-level license files whose terms require the file to travel with the assets (currently only spine) are co-located under public/ alongside them.
• Versions — package.json pins playcanvas: "latest" + @playcanvas/observer; README notes the exact authoring version in case a newer release differs.

Testing

• Verified end-to-end with Playwright: clicking Download produces misc-hello-world.zip; unzipped → npm i && npm run dev renders the example, with imports rewritten and the @config block stripped.
• Toolbar styling checked across examples (with/without a controls tab).
• Attribution verified via the real in-browser buildProjectZip:
  • graphics/shadow-catcher → CREDITS.md (Poly Haven, CC BY 4.0), asset still bundled.
  • gaussian-splatting/first-person (remote S3 splat, no local license) → CREDITS.md (Sunnyvale, CC BY 4.0).
  • misc/spineboy → CREDITS.md and co-located public/assets/spine/license.txt.
  • Non-attributed examples build with no CREDITS.md and make no extra license fetches.

[mvaligursky]

any way we can preserve the CC licenses for assets the example uses?

[kpal81xd]

any way we can preserve the CC licenses for assets the example uses?

Yep just done