fix: allow @, +, and Unicode branch names

[Lubrsy706]

Summary

Fixes #998 and #1020

The whitelist regex in validateBranchName (src/github/operations/branch.ts) previously rejected valid git branch names containing @, +, or non-ASCII Unicode characters.

Changes

• update src/github/operations/branch.ts to allow @, +, and Unicode letters/numbers in branch names
• keep rejecting Git-reserved patterns like @{, .lock, .., consecutive /, and invalid ref characters
• extend test/validate-branch-name.test.ts with coverage for + alongside the existing @ and Unicode cases

Security

The @{ reflog syntax is still rejected explicitly. Control characters, shell metacharacters, and Git-special characters like ~, ^, :, ?, *, [, ], and \ remain blocked. The validator still forbids names that could trigger option injection or path traversal.

Test plan

• bun test test/validate-branch-name.test.ts
• bun run typecheck

[Lubrsy706]

Friendly ping: this PR has been ready for review since March 6, 2026. If there is anything blocking it or if you would prefer changes before merge, let me know and I can update it. Would appreciate a review when someone has time.

[Lubrsy706]

Updated this PR to include + as well. Git accepts branch names like feature+x, so the validator now allows @, +, and Unicode branch names while still rejecting reserved/unsafe patterns like @{, .lock, .., and invalid ref characters. I also added test coverage for the + case and reran the branch-name tests plus typecheck.

[Lubrsy706]

Following up on this PR. The branch-name handling change should be ready for review; please let me know if you'd like any updates or additional test coverage from my side.

[Lubrsy706]

Rebased this branch onto the latest main and resolved the merge conflicts. The branch-name validation changes now include #, @, +, and Unicode support together, and I reran bun test test/validate-branch-name.test.ts after the rebase. PR should now be conflict-free and ready for review.

[Lubrsy706]

Following up on this PR. The branch-name handling fix should be ready for review; if you would like any adjustments or broader coverage for special-character branch names, I can update it. Would appreciate a review when someone has time.