feat: unified gravity system - VIP members consume gravity instead of unlimited; add monthly gravity top-up cron

backend/src/modules/schedule/schedule.module.ts

@@ -3,8 +3,10 @@ import { MongooseModule } from '@nestjs/mongoose'
 import { DailyQuestionPushService } from './daily-question-push.service'
 import { WechatTokenService } from './wechat-token.service'
 import { VipExpiryService } from './vip-expiry.service'
+import { GravityTopUpService } from './gravity-top-up.service'
 import { DailyQuestion, DailyQuestionSchema } from '../schemas/daily-question.schema'
 import { User, UserSchema } from '../user/user.schema'
+import { PricingService } from '../schemas/pricing.service'
 
 @Module({
   imports: [
@@ -13,6 +15,6 @@ import { User, UserSchema } from '../user/user.schema'
       { name: User.name, schema: UserSchema },
     ]),
   ],
-  providers: [WechatTokenService, DailyQuestionPushService, VipExpiryService],
+  providers: [WechatTokenService, DailyQuestionPushService, VipExpiryService, GravityTopUpService, PricingService],
 })
 export class ScheduleModule {}