feat: integrate ConfigModule and DatabaseModule into app initialization

backend/src/app.module.ts

@@ -1,9 +1,14 @@
 import { Module } from "@nestjs/common";
 import { AppController } from "./app.controller";
 import { AppService } from "./app.service";
+import {DatabaseModule} from "./database/database.module";
+import {ConfigModule} from "@nestjs/config";
 
 @Module({
-	imports: [],
+	imports: [DatabaseModule,
+		ConfigModule.forRoot({
+			isGlobal: true,
+		})],
 	controllers: [AppController],
 	providers: [AppService],
 })