feat(distribution): 分站可下调收号比例且不超过主站上限

让分销站能按自身能力下调收号比例扩大利润，同时把主站回收比例作为硬边界，避免分站把比例加得比主站更高。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/features/seller/composables/usePublishForm.ts

@@ -34,6 +34,7 @@ import {
 import type { PublishForm } from '@/shared/types/publish'
 import { yuanToCent } from '@/shared/utils/money'
 import { dailyLossOptions, formatNumber, roundRatio } from '@/shared/utils/pricing'
+import { useDistributionSiteStore } from '@/stores/distributionSite'
 
 const draftSaveDelay = 400
 const multiScreenshotLimit = 3
@@ -54,6 +55,9 @@ interface UsePublishFormOptions {
 export function usePublishForm(options: UsePublishFormOptions) {
   const router = useRouter()
   const route = useRoute()
+  const siteStore = useDistributionSiteStore()
+  const isDistribution = computed(() => siteStore.isDistribution)
+  const receiveRatioDelta = computed(() => Number(siteStore.receiveRatioDelta || 0))
   const loading = ref(false)
   const uploading = ref(false)
   const suppressDraftSave = ref(false)
@@ -89,6 +93,8 @@ export function usePublishForm(options: UsePublishFormOptions) {
     quantityModes,
     screenshotFiles,
     selectedSkins,
+    isDistribution,
+    receiveRatioDelta,
   })
 
   // ========== 上号方式互斥 ==========
@@ -911,6 +917,7 @@ export function usePublishForm(options: UsePublishFormOptions) {
 
   return {
     ...pricing,
+    isDistribution,
     dailyLossOptions,
     formatNumber,
     router,