feat(combat): add combat domain enums, entities, and encounter consumption field

apps/api/src/hunting/entities/hunt-encounter.entity.ts

@@ -23,6 +23,11 @@ export class HuntEncounter {
   @Column({ name: 'position', type: 'integer' })
   position!: number;
 
+  // Set when a Combat is successfully created from this encounter. Prevents
+  // one HuntEncounter from spawning more than one Combat (spec §7).
+  @Column({ name: 'consumed_at', type: 'timestamptz', nullable: true })
+  consumedAt!: Date | null;
+
   @CreateDateColumn({ name: 'created_at', type: 'timestamptz' })
   createdAt!: Date;