lint-registry-items.mjs reports missing assets that the item manifest declares #7279

scripts/lint-registry-items.mjs copies only <name>.html into a temporary project before linting, and ignores the files each item's manifest lists under files[].target. Items that ship assets then fail with missing_local_asset. Running it over all 449 registry items currently exits with "24 registry item(s) have lint errors", and some of those are false. For example, yt-lower-third reports assets/avatar.jpg missing even though its manifest declares it, and texture-mask-text declares 67 mask files.

Scope

• Install every file the manifest lists at its target path before linting.
• Optional: read hyperframes lint --json instead of matching ✗ lines in the output.

Files: scripts/lint-registry-items.mjs, a new test, root package.json

Done when: yt-lower-third and texture-mask-text lint clean, and a fixture test covers an item that ships an asset. Real findings on other items are out of scope.

Mentor: @jrusso1020. Comment here before you start so we can avoid duplicate PRs.