feat: Introduce new modules for class, inventory, leveling, and quests with expanded schema, refactor user service, and add verification scripts.

drizzle.config.ts

@@ -1,6 +1,11 @@
 import { defineConfig } from "drizzle-kit";
 import { env } from "./src/lib/env";
 
+// @ts-expect-error - Polyfill for BigInt serialization
+BigInt.prototype.toJSON = function () {
+    return this.toString();
+};
+
 export default defineConfig({
     schema: "./src/db/schema.ts",
     out: "./drizzle",