fix: formatting with prettier not working in non skeleton repos

[fredericoo]

WHY are these changes introduced?

Since we moved to pnpm prettier has been silently failing in code changes that are not the skeleton: because npm used to hoist the @shopify/prettier-config package from skeleton to the root of the monorepo, we were able to run it in other places.

Oh and we were not checking or formatting the skeleton template!

WHAT is this pull request doing?

• adding @shopify/prettier-config at the root package.json
• standardised version with catalog:
• added ./templates to formating and checks

HOW to test your changes?

• change the formatting a file outside skeleton (like a test)
• format it
• check output of prettier if you are on vscode and use the extension to ensure it loaded it all good

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or noteworthy changes
• I've added tests to cover my changes
• I've added or updated the documentation

[shopify]

Oxygen deployed a preview of your fb-fix-prettier-root branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	February 26, 202612:27 PM

Learn more about Hydrogen's GitHub integration.

[fredericoo]

we might want to add templates here as well, but i opted not to touch linting right now

[andguy95]

LGTM! 💅

[fredericoo]

Merge activity

• Feb 26, 5:31 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Feb 26, 5:31 PM UTC: @fredericoo merged this pull request with Graphite.