feat(messages): integrate UsersModule into MessagesModule with forward-ref

- Added `UsersModule` to `MessagesModule` imports using `forwardRef`.
- Injected `UsersService` into `MessagesService` to support user-related operations.

backend/src/messages/messages.module.ts

@@ -1,12 +1,13 @@
-import { Module } from "@nestjs/common";
+import { forwardRef, Module } from "@nestjs/common";
 import { AuthModule } from "../auth/auth.module";
 import { RealtimeModule } from "../realtime/realtime.module";
+import { UsersModule } from "../users/users.module";
 import { MessagesController } from "./messages.controller";
 import { MessagesService } from "./messages.service";
 import { MessagesRepository } from "./repositories/messages.repository";
 
 @Module({
-	imports: [AuthModule, RealtimeModule],
+	imports: [AuthModule, RealtimeModule, forwardRef(() => UsersModule)],
 	controllers: [MessagesController],
 	providers: [MessagesService, MessagesRepository],
 	exports: [MessagesService],