Adds Task 1 of Playable Slice 0.2: pure entity/enum/helper definitions for the Hunt/Encounter system (MonsterDefinition, LocationMonster, Hunt, HuntEncounter, EncounterType, HuntStatus, RandomSource, DangerRating). No DB migration, module wiring, or seed data yet. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>