chore(package): add repository field

[barinali]

Proposed Changes

I realized we are lacking the repository field when np command did not create the draft release on GH.

Checklist

Ensure you provide everything we need to review your contribution:

• Contribution meets our definition of done
• Pull request establishes context
  • Link to related issue(s), i.e. Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}
  • Brief textual description of the changes
  • Screenshots or short videos showing UI/UX changes
  • Steps to try out, i.e. using the @bpmn-io/sr tool

[Copilot]

Pull request overview

Adds missing repository metadata to package.json so tooling like np can correctly detect the GitHub repository and create draft releases.

Changes:

• Add repository field (type + URL) to npm package metadata.

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