refactor(skill): rewrite claude skill for expert knowledge density (#47)

refactor(skill): rewrite claude skill from 498 to ~165 lines

Concentrate the skill on expert knowledge instead of command reference docs.

- Replace 11 individual command sections with one routing table
- Consolidate scattered anti-patterns into one NEVER list
- Merge duplicate worktree sections into one
- Fix bug: `morg completion` → `morg shell-init`
- Remove unsupported `allowed-tools` frontmatter
- Expand trigger keywords in description
- Add git worktrees section to CLAUDE.md
- Update worktree guidance: use `pnpm install` (fast via store)
  instead of manual node_modules symlinks
- Revert accidental pnpm v11 packageManager field

Author: developerdavi