Ignore .claude/ directory (#28)

Claude Code creates isolation worktrees under .claude/worktrees, which
showed up as untracked changes in the main repo. Ignore the whole
.claude/ tree so per-user harness state doesn't leak into git status.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: KaliCZ

.gitignore

@@ -9,3 +9,4 @@
 src/packages
 src/.idea
 .idea/
+.claude/