feat: gravity transaction logging + user-facing history popup

- New GravityTransaction schema tracks all gravity changes (registration,
  interview/optimize/download deduction, purchase, monthly topup, migration)
- GravityTopUpService: bulk log for monthly VIP topup
- PaymentController.activateMembership: log plan_set transactions
- QuotaService: add logTransaction, wire into all gravity-modifying methods
- UserService: log registration grants (phone/wx/email/password)
- GET /user/gravity-transactions?page=&limit= API
- Frontend: user.vue '明细' button + paginated popup
- Docs: update PROJECT-STATUS v4.10, FEATURE-LIST, DEPLOYMENT

backend/src/modules/payment/payment.controller.spec.ts

@@ -51,6 +51,7 @@ describe('PaymentController', () => {
       providers: [
         { provide: getModelToken('User'), useValue: mockUserModel },
         { provide: getModelToken('PaymentOrder'), useValue: mockOrderModel },
+        { provide: getModelToken('GravityTransaction'), useValue: { create: jest.fn() } },
         { provide: WechatPayService, useValue: mockWechatPay },
         { provide: QuotaService, useValue: mockQuotaService },
         { provide: PricingService, useValue: mockPricingService },

backend/src/modules/payment/payment.controller.ts

@@ -9,6 +9,7 @@ import { WechatPayService } from './wechat-pay.service'
 import { QuotaService } from '../user/quota.service'
 import { PricingService } from '../schemas/pricing.service'
 import { Public } from '../../common/decorators/public.decorator'
+import { GravityTransaction } from '../schemas/gravity-transaction.schema'
 
 @Controller('payment')
 export class PaymentController {
@@ -17,6 +18,7 @@ export class PaymentController {
   constructor(
     @InjectModel(User.name) private userModel: Model<UserDocument>,
     @InjectModel(PaymentOrder.name) private orderModel: Model<PaymentOrderDocument>,
+    @InjectModel(GravityTransaction.name) private gravityTxModel: Model<GravityTransaction>,
     private wechatPay: WechatPayService,
     private quotaService: QuotaService,
     private pricingService: PricingService,
@@ -226,6 +228,14 @@ export class PaymentController {
     user.gravity = planCfg.gravityPerMonth
     user.freeOptimizeUsed = 3
     await user.save()
+    await this.gravityTxModel.create({
+      userId: order.userId,
+      amount: planCfg.gravityPerMonth,
+      balance: planCfg.gravityPerMonth,
+      type: 'plan_set',
+      description: `开通${isSprint ? '冲刺版' : '成长版'}会员，获得 ${planCfg.gravityPerMonth} 引力值`,
+      refId: order.outTradeNo,
+    })
   }
 
   private async activateProduct(order: PaymentOrderDocument) {