chore(gitignore): ignore .claude/worktrees/ (transient agent worktrees)

Claude Code worktree-isolated agents create per-agent git worktrees
under .claude/worktrees/. These are transient scratch checkouts and must
never be committed — committing a nested worktree would corrupt the
repo. Ignoring the path keeps the working tree clean while an agent runs.

Author: claude

.gitignore

@@ -107,3 +107,7 @@ packages/affine-js/deno.lock
 
 # ADR-015 S3: fetch-pinned WASI adapter (provisioned, not committed)
 tools/vendor/
+
+# Claude Code agent worktrees — transient per-agent git worktrees,
+# never committed (committing a nested worktree would corrupt the repo).
+/.claude/worktrees/