chore: add CLAUDE.md to .gitignore

Keep Claude Code project notes local-only so branch configuration
doesn't get committed to the repository.

https://claude.ai/code/session_01Y2eJZgKG78nDyN6Uw2tWQx

Author: claude

.gitignore

@@ -23,3 +23,6 @@ test-scripts/.install-test/
 
 # Claude Code temporary worktrees
 .claude/worktrees/
+
+# Claude Code project notes (local only)
+CLAUDE.md