Refactor Study Desk application structure

src/services/healthService.ts

@@ -0,0 +1,8 @@
+import { prisma } from "@/lib/db";
+
+export async function checkApplicationHealth() {
+  await prisma.$transaction([
+    prisma.deck.findFirst({ select: { id: true, groupId: true } }),
+    prisma.materialGroup.count(),
+  ]);
+}