Implement login, add useUser hook

services/user/findUserByEmail.ts

@@ -0,0 +1,13 @@
+import DBClient from '@/prisma/DBClient';
+
+const findUserByEmail = async (email: string) =>
+  DBClient.instance.user.findFirst({
+    where: { email },
+    select: {
+      id: true,
+      username: true,
+      hash: true,
+    },
+  });
+
+export default findUserByEmail;