feat(combat): add HTTP controllers for starting, reading, and acting on combats

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/api/src/combat/combat.controller.ts

@@ -0,0 +1,19 @@
+import { Body, Controller, Get, Param, Post } from '@nestjs/common';
+import { DEMO_CHARACTER_ID } from '../demo/demo-character.constants';
+import { CombatActionDto } from './dto/combat-action.dto';
+import { CombatService } from './combat.service';
+
+@Controller('combats')
+export class CombatController {
+  constructor(private readonly combatService: CombatService) {}
+
+  @Get(':combatId')
+  getCombat(@Param('combatId') combatId: string) {
+    return this.combatService.getCombat(DEMO_CHARACTER_ID, combatId);
+  }
+
+  @Post(':combatId/actions')
+  performAction(@Param('combatId') combatId: string, @Body() dto: CombatActionDto) {
+    return this.combatService.performAction(DEMO_CHARACTER_ID, combatId, dto.action);
+  }
+}