feat: add HelpText model, service, and controller for dynamic help text management

backend/src/app.module.ts

@@ -17,6 +17,7 @@ import { UserProductsModule } from './user-products/user-products.module';
 import { CategoriesModule } from './categories/categories.module';
 import { AiModule } from './ai/ai.module';
 import { RealtimeModule } from './realtime/realtime.module';
+import { HelpTextsModule } from './help-texts/help-texts.module';
 import { JwtAuthGuard } from './auth/jwt-auth.guard';
 import { RolesGuard } from './auth/roles.guard';
 
@@ -46,6 +47,7 @@ import { RolesGuard } from './auth/roles.guard';
     CategoriesModule,
     AiModule,
     RealtimeModule,
+    HelpTextsModule,
   ],
   providers: [
     {