chore: add .worktrees/ to .gitignore

Prevent worktree contents from being tracked in the repository.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: mithro

.gitignore

@@ -140,3 +140,6 @@ cython_debug/
 # Generated version file
 actions_includes/version.py
 docker/*.tar.gz
+
+# Git worktrees
+.worktrees/