chore: custom changesets plugin

[castastrophe]

Description

This PR implements a custom changesets changelog plugin for GitHub that improves the changelog generation process. The changes include:

• Custom changelog plugin: Created @spectrum-tools/changesets-changelog-github plugin to replace the standard @changesets/changelog-github
• Enhanced formatting: Added emoji prefix (📝) and improved spacing in changelog entries
• Better commit handling: Simplified commit link generation and improved test coverage
• Dependency updates: Updated dotenv from ^16.4.7 to ^16.5.0
• CI integration: Added distinct GitHub token environment variable for plugin's access to user's GitHub username and reading pull request titles.

The plugin provides better control over changelog formatting and ensures consistent output across releases.

How and where has this been tested?

Please tag yourself on the tests you've marked complete to confirm the tests have been run by someone other than the author.

Validation steps

1. Plugin functionality testing:

   • Run yarn test:plugins to verify the custom changelog plugin works correctly
   • Verify that changelog entries are properly formatted with emoji prefix and correct spacing
   • Test that commit links are generated correctly with shortened commit hashes

2. Changeset integration testing:

   • Verify that .changeset/config.json correctly references the new custom plugin
   • Test that the plugin generates proper changelog entries for PRs and commits
   • Confirm that the plugin handles multiple authors and various commit formats correctly

3. CI/CD pipeline testing:

   • Verify that the GitHub workflow includes the necessary environment variable for plugin testing
   • Test that the plugin tests run successfully in the CI environment

Regression testing

Validate:

1. The documentation pages for at least two other components are still loading, including:

• The pages render correctly, are accessible, and are responsive.

2. If components have been modified, VRTs have been run on this branch:

• VRTs have been run and looked at.
• Any VRT changes have been accepted (by reviewer and/or PR author), or there are no changes.

To-do list

• I have read the contribution guidelines.
• I have updated relevant storybook stories and templates.
• I have tested these changes in Windows High Contrast mode.
• If my change impacts other components, I have tested to make sure they don't break.
• If my change impacts documentation, I have updated the documentation accordingly.
• ✨ This pull request is ready to merge. ✨

Additional testing completed:

• Plugin unit tests pass with updated test expectations
• Changeset configuration properly references the custom plugin
• Dependency updates are compatible and secure
• CI workflow includes necessary environment variables for testing

[changeset-bot]

⚠️ No Changeset found

Latest commit: 4f35524

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[github-actions]

File metrics

Summary

Total size: 2.25 MB^*

🎉 No changes detected in any packages

* Size is the sum of all main files for packages in the library.
* An ASCII character in UTF-8 is 8 bits or 1 byte.

[github-actions]

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