Register public.data and modern developer formats so MacVim appears in Finder's "Open With"

[oxngon]

What this does

Adds two CFBundleDocumentTypes entries to src/MacVim/Info.plist so MacVim appears in Finder's right-click → "Open With" menu for files it isn't offered for today.

Fixes #1704.

1. public.data at LSHandlerRank = Alternate — dotfiles and extensionless files (.zshrc, .env, .gitignore, Dockerfile). mdls reports these as public.data, and no document type claims it at the moment.
2. public.json / public.yaml at LSHandlerRank = Alternate, plus CFBundleTypeExtensions for toml, ts, tsx, jsx, mjs, cjs, astro, svelte, graphql, gql, vue, go, rs. public.toml and public.configuration don't exist as system UTIs, hence plain extensions for those.

Why Alternate

So MacVim appears in the "Open With" menu without ever being made the default handler and without taking over icons or file associations — including for public.data, which is the fallback type for every file Launch Services can't classify more precisely. Other macOS editors handle it the same way: Zed ships public.plain-text / public.text / public.utf8-plain-text at Alternate, and SilentText ships public.data at Alternate. Happy to switch the developer-format entry to Default if you'd rather.

Scope

• No change to UTExportedTypeDeclarations — this only adds claims. The exported-type registrations discussed in MacVim exports standard UTIs, and does it wrongly, messing up the system #916 / UTI registrations are wrong #1169 are untouched.
• The diff is a pure append: +41 / −0. No reformatting, and the "when adding support for a new file type" comment at the top of the plist is preserved.
• Sequencing with the open Fix incorrect UTI registrations #1489: that PR rewrites the same file to use LSItemContentTypes and adds public.plain-text / public.source-code / public.script / public.shell-script, but none of the types here. Tell me if you'd rather I rebase Fix incorrect UTI registrations #1489 and fold these in, or trim this to only the public.data entry — either is a small change.

Testing

There's no test harness for bundle metadata as far as I can tell, so this is verified by inspection rather than by a test: the patched plist parses cleanly, CFBundleDocumentTypes goes from 76 to 78 entries, and that key is the only one that changes. The public.data claim matches the mdls output included in #1704.

AI disclosure

AI assistance was used to prepare this patch. The diff was validated and I reviewed it before submitting.