fix(repository): support full git refs

[dannyward630]

Summary

• fetch requested repository refs directly instead of forcing them through refs/heads/*
• checkout branch refs as local branches and non-branch refs detached from FETCH_HEAD
• allow safe full refs such as refs/tags/effect@4.0.0-beta.65 in repository reference validation
• cover full tag refs in git and repository cache tests

Closes #32861

Verification

• bun test test/git.test.ts test/repository.test.ts test/repository-cache.test.ts --timeout 30000
• bun run typecheck
• bun turbo typecheck

[github-actions]

This PR doesn't fully meet our contributing guidelines and PR template.

What needs to be fixed:

• PR description is missing required template sections. Please use the PR template.

Please edit this PR description to address the above within 2 hours, or it will be automatically closed.

If you believe this was flagged incorrectly, please let a maintainer know.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Duplicate Found

PR #32863 - fix(core): support reference refs
#32863

This appears to be related to PR #32898. The PR description mentions "Closes #32861", which suggests it addresses the same issue. The similar scope ("support reference refs" vs "support full git refs") and timing indicate these PRs are likely addressing the same feature or closely related changes in git ref handling.

[github-actions]

This pull request has been automatically closed because it was not updated to meet our contributing guidelines within the 2-hour window.

Feel free to open a new pull request that follows our guidelines.