Keep Claude Code's agent worktrees out of the repository

.claude/worktrees/ holds complete working copies -- during a parallel agent run
there were six, each a full checkout with its own build output. None of it is
tracked, so it sat in `git status` as untracked noise, and a `git add -A` at the
wrong moment would have committed the repository into itself.
scheduled_tasks.lock is equally machine-local.

Both are named individually rather than ignoring .claude/ wholesale. That
directory is also where shared project config lives -- settings.json, agents/,
skills/ -- and ignoring the parent would have pre-emptively hidden files a
project would normally commit, for no benefit today.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitignore

@@ -17,3 +17,10 @@ local.properties
 # The FFmpeg AAR is committed under bin/ so test runs do not depend on a rebuild.
 # Build outputs from tools/ffmpeg are not.
 tools/ffmpeg/out/
+
+# Claude Code's per-machine state. Named file by file rather than ignoring .claude/, so that
+# shared project config -- settings.json, agents/, skills/ -- stays committable if this project
+# ever adopts it. worktrees/ holds complete working copies: during a parallel agent run there
+# were six, each a full checkout with its own build output.
+.claude/worktrees/
+.claude/scheduled_tasks.lock