use @prisma/adapter-pg with PrismaClient (required by prisma v7)

backend/package.json

@@ -27,6 +27,7 @@
     "@nestjs/platform-socket.io": "^11.1.24",
     "@nestjs/swagger": "^11.4.4",
     "@nestjs/websockets": "^11.1.24",
+    "@prisma/adapter-pg": "^7.8.0",
     "@prisma/client": "^7.8.0",
     "bcryptjs": "^3.0.3",
     "class-transformer": "^0.5.1",
@@ -34,6 +35,7 @@
     "multer": "^2.1.1",
     "passport": "^0.7.0",
     "passport-jwt": "^4.0.1",
+    "pg": "^8.21.0",
     "prisma": "^7.8.0",
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.2",
@@ -47,6 +49,7 @@
     "@types/multer": "^2.1.0",
     "@types/node": "^25.9.1",
     "@types/passport-jwt": "^4.0.1",
+    "@types/pg": "^8.20.0",
     "ts-node": "^10.9.2",
     "tsconfig-paths": "^4.2.0",
     "typescript": "^6.0.3"