refactor: fix stale imports

shared/modules/class/class.service.ts

@@ -1,7 +1,7 @@
 import { classes, users } from "@db/schema";
 import { eq, sql } from "drizzle-orm";
 import { DrizzleClient } from "@shared/db/DrizzleClient";
-import { UserError } from "@/lib/errors";
+import { UserError } from "@shared/lib/errors";
 import { withTransaction } from "@/lib/db";
 import type { Transaction } from "@shared/lib/types";