chore: update Prisma and dependencies, add initial migration and tests

- Updated Prisma and @prisma/client to version 6.19.2 in package.json and yarn.lock.
- Added package extensions for @prisma/client in .yarnrc.yml.
- Updated backend README.md for clearer setup instructions.
- Created initial migration for Game, Platform, and related tables in Prisma.
- Added migration lock file for version control.
- Implemented tests for Game model using Vitest, including creation and unique slug constraint checks.

backend/package.json

@@ -9,9 +9,11 @@
     "build": "tsc -p tsconfig.json",
     "start": "node dist/index.js",
     "test": "vitest",
-    "prisma:generate": "prisma generate",
-    "prisma:migrate": "prisma migrate dev --name init",
-    "prisma:studio": "prisma studio",
+    "test:ci": "vitest run",
+    "prisma:generate": "prisma generate --schema=./prisma/schema.prisma",
+    "prisma:migrate": "prisma migrate dev --name init --schema=./prisma/schema.prisma",
+    "prisma:migrate:deploy": "prisma migrate deploy --schema=./prisma/schema.prisma",
+    "prisma:studio": "prisma studio --schema=./prisma/schema.prisma",
     "lint": "eslint \"src/**/*.{ts,js}\"",
     "format": "prettier --write ."
   },
@@ -20,7 +22,7 @@
     "@fastify/helmet": "^11.0.0",
     "@fastify/multipart": "^9.0.0",
     "@fastify/rate-limit": "^9.0.0",
-    "@prisma/client": "5.22.0",
+    "@prisma/client": "6.19.2",
     "dotenv": "^16.0.0",
     "fastify": "^4.28.0",
     "pino": "^8.0.0"
@@ -29,7 +31,7 @@
     "@types/node": "^18.0.0",
     "eslint": "^8.0.0",
     "prettier": "^2.8.0",
-    "prisma": "5.22.0",
+    "prisma": "6.19.2",
     "ts-node-dev": "^2.0.0",
     "typescript": "^5.2.0",
     "vitest": "^0.31.0"