feat(api): add inventory API (GET /api/inventory)

apps/api/src/inventory/inventory.controller.ts

@@ -0,0 +1,13 @@
+import { Controller, Get } from '@nestjs/common';
+import { DEMO_CHARACTER_ID } from '../demo/demo-character.constants';
+import { InventoryResponseDto, InventoryService } from './inventory.service';
+
+@Controller('inventory')
+export class InventoryController {
+  constructor(private readonly inventoryService: InventoryService) {}
+
+  @Get()
+  getInventory(): Promise<InventoryResponseDto> {
+    return this.inventoryService.getInventory(DEMO_CHARACTER_ID);
+  }
+}