superpower skills

Key features

• Later layers (profile's cordis.patch.yml, --patch overlay) can still locate this row by id.
• Removed namespace prefixsuperpowers:brainstorming → brainstorming (DSH skills are addressed with bare names).
• Provider - lib/index.js calls ctx.skills.registerProvider(...) to register a provider
• list() scans the skills/ directory in the package, takes each /SKILL.md as a candidate, and parses name, description, and whenToUse from YAML frontmatter.
• get() reads the candidate skill text on demand and returns the complete skill definition. The resourceBase points to the directory where the skill is located so that relative references (scripts, prompt templates) can be parsed correctly.