Version-exclusive bosses (e.g., Bea in Sword, Allister in Shield) were
using the section field to indicate which game they belong to. This adds
a proper game_id foreign key so the API can filter bosses per game,
keeping section free for visual grouping like "Main Story".
- Alembic migration adds nullable game_id column with FK and index
- API list_bosses filters by game_id unless ?all=true is passed
- Seed data updated to use game_slug instead of section overloading
- Admin form adds "Game (version exclusive)" dropdown
- Export endpoints include game_slug for exclusive bosses
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>