fix: import dependency-heavy Open VSX themes

[Yukaii]

Summary

• raise the Open VSX archive entry limit from 2,000 to 5,000
• raise the declared uncompressed-size limit from 50 MB to 100 MB
• keep the existing download, compression-ratio, theme-file, checksum, path, and include-depth protections unchanged

Mirrors the package-limit adjustment from pingdotgg/t3code#7642.

Validation

• bun run build
• bun run lint
• bunx oxfmt --check src/lib/openVsxThemes.ts
• imported a generated 3,005-entry VSIX through the public importer

Repository-wide bun run format:check still reports pre-existing formatting issues in src/components/KeyboardHelp.vue and src/pages/SearchPage.vue.