api/firstRun.post: properly initialize database using @prisma/migrate

instead of executing the command,
which was not available in the build
now we use the proper library to initialize the database.

package.json

@@ -24,6 +24,7 @@
   },
   "dependencies": {
     "@prisma/client": "5.5.2",
+    "@prisma/migrate": "^5.5.2",
     "mysql2": "^3.2.3"
   }
 }