test(integration): add lightweight MySQL-backed API smoke tests for center and guild

Fabric.Backend.Guild/package.json

@@ -10,7 +10,8 @@
     "lint": "eslint 'src/**/*.ts'",
     "lint:fix": "eslint 'src/**/*.ts' --fix",
     "format": "prettier --write 'src/**/*.ts'",
-    "test:unit": "vitest run"
+    "test:unit": "vitest run",
+    "test:integration": "vitest run src/*.integration.spec.ts"
   },
   "dependencies": {
     "@nestjs/common": "^10.4.8",
@@ -28,12 +29,15 @@
   },
   "devDependencies": {
     "@eslint/js": "^10.0.1",
+    "@nestjs/testing": "^10.4.22",
     "@types/node": "^22.10.1",
+    "@types/supertest": "^7.2.0",
     "@typescript-eslint/eslint-plugin": "^8.59.3",
     "@typescript-eslint/parser": "^8.59.3",
     "eslint": "^10.3.0",
     "eslint-config-prettier": "^10.1.8",
     "prettier": "^3.8.3",
+    "supertest": "^7.2.2",
     "ts-node": "^10.9.2",
     "typescript": "^5.7.2",
     "vitest": "^4.1.6"