New command that spawns background agents to work on multiple issues simultaneously, each in an isolated git worktree. - commands/spawn-issues.md: Entry point, parses args, spawns agents - agents/issue-worker/agent.md: Autonomous agent that implements a single issue (worktree setup, implement, PR, cleanup) Worktrees are automatically cleaned up after PR creation. Branch remains on remote for follow-up work if needed. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>