Ignore local .claude/ tooling state

Agent worktrees created by the Claude Code harness live under .claude/
and are ephemeral, session-local scratch space, not repository content.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4RQ1Ahan5YAGbnAQGjZTY

.gitignore

@@ -45,3 +45,6 @@ nlohmann_json.spdx
 
 # Bazel-related
 MODULE.bazel.lock
+
+# Claude Code local tooling state (agent worktrees, etc.)
+/.claude/