Source branch validation

[CringeCursed]

Short description

Add GitHub Actions workflow to validate that PR branches are created from starlight-dev

Why we need to add this

This PR adds a new GitHub Actions workflow that enforces proper branch management by validating the source of pull request branches. The workflow uses git history analysis to ensure branches are properly derived from starlight-dev.

Technical implementation:

• Uses git merge-base to find the common ancestor between the PR branch and starlight-dev
• Performs two-step validation:
  • Checks if the base commit is an ancestor of starlight-dev
  • Verifies the base commit is also an ancestor of the current starlight-dev HEAD
• On validation failure:
  • Automatically adds a comment with rebase instructions using actions/github-script
• Uses fetch-depth: 0 to ensure full git history is available for accurate ancestry checking

The strict ancestry checking ensures that branches haven't diverged from an old version of starlight-dev

Media (Video/Screenshots)

Checks

• I do not require assistance to complete the PR.
• Before posting/requesting review of a PR, I have verified that the changes work.
• I have added screenshots/videos of the changes, or this PR does not change in-game mechanics.
• I affirm that my changes are licensed under the Starlight Fork License and grant permission for use in this repository under its conditions.

Changelog
🆑 Cringe_Cursed

• add: Added GitHub Actions workflow for validating PR branch origins against starlight-dev

[CringeCursed]

[CringeCursed]

yappy 😀

[Conflee]

Originate from starlight-dev or are being PRed TO starlight-dev? If its the first I am never PRing again because I can't get that working.

[CringeCursed]

Originate from starlight-dev or are being PRed TO starlight-dev? If its the first I am never PRing again because I can't get that working.