Allow users to define custom workflow stages beyond the default 15.\n\nRequirements:\n- Stage schema definition file (YAML/JSON)\n- Stage registration in opencode.json\n- Custom SKILL.md template generator\n- Validation against stage interface\n\nThis is the core v2.0 feature from ROADMAP.md.
Allow users to define custom workflow stages beyond the default 15.\n\nRequirements:\n- Stage schema definition file (YAML/JSON)\n- Stage registration in opencode.json\n- Custom SKILL.md template generator\n- Validation against stage interface\n\nThis is the core v2.0 feature from ROADMAP.md.