Add two new Claude Code slash commands:
- generate-agents.md.md: Generate hierarchical AGENTS.md structures
- refactor-agents.md.md: Refactor existing AGENTS.md files
Changes to siren script:
- Make Claude symlinks conditional on CLI installation
- Extract _add_command_symlinks() for reusable command symlinking
- Extract _cleanup_stale_commands() for generic stale link cleanup
- Add plan mode instructions to CLAUDE.md
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
