Progress Through Islands

## story: Progress Through Islands ### Role Kid (Lucas's child) ### Key progress ### Want As a **kid**, I want to **complete islands by filling musical parts and unlock new islands** ### So That So that **I can earn new monster vibes and build new songs** ### Acceptance Criteria - Islands are levels with a level_number and theme - Placing enough monsters (3+ of 6 parts) completes the island - Completing an island rewards a new monster (new vibe for an existing part) - Completing an island unlocks the next island - Later islands unlock more vibes per part -- kids gain expressive range as they progress - Player's current_level tracks progression - Monster.level_unlocked controls catalog growth across levels ### Success Metric Complete island 1, win monster, unlock island 2. ### Related Architecture - `arch-domain-lil-beasties` -- Island.level_number, Island.completed, Monster.level_unlocked ### Related - `project-lil-beasties` -- parent project page - `board-lil-beasties` -- project board - `docs/music-theory.md` in repo -- completion threshold, catalog growth