style: make searcher result buttons full width

[with-heart]

Howdy! Just poking around in the codebase and noticed an opportunity for a minor improvement.

This change makes the searcher result items full width:

Previously, they only took up the width of their contents, resulting in inconsistent click targets:

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🔍 Inspect: https://vercel.com/mattpocock/xstate-catalogue/9qshq3pnbxjAathZAxbU2FMs7KMe
✅ Preview: https://xstate-catalog-git-fork-with-heart-full-width-searcher-r-a5cf8a.vercel.app

[mattpocock]

Nice! Instant merge!

[mattpocock]

@all-contributors please add @with-heart for code

[allcontributors[bot]]

@mattpocock

I've put up a pull request to add @with-heart! :tada: