Adds Combat domain models (Combat, CombatPlayer, CombatMonster, CombatEvent)
and three GameApiService methods to interact with backend combat endpoints:
- startCombat(encounterId): POST /api/hunt-encounters/:id/attack
- getCombat(combatId): GET /api/combats/:id
- performCombatAction(combatId, action): POST /api/combats/:id/actions
Includes test coverage for all three methods.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>