feat(distribution): 分站收号压价解耦买家价（方案 B 新口径）

核心语义反转：receive_cost_delta 为压价点数，收号比例 = 主站参考比例 R + 点数，
点数越大号主收号价越低；买家售价锚定主站参考比例推导，不再随收号价联动。

- 迁移 000072：distribution_sites 新增 receive_cost_delta（旧 receive_ratio_delta 保留只读）
- receive_pricing：新增 Normalize/ApplySiteReceiveCostDelta；分站定价买家侧改用
  R 锚点（referenceSellerCoinBasePrice），快照写入 site_receive_cost_delta 与 pricing_model 标记
- site_receive：新增 resolveSiteReceiveCostDelta 读取链路，旧 ResolveReceiveRatioDelta 保留
- 分成不变：压价差经结算层 profit 自动进入 35/40/25 三方分成池；
  货架自主加价仍 100% 归分站，两条边界均以主站为锚
- 权限对齐旧字段：主站全局管理员与分站操作员均可设置
- 前端三端同步：主站 pricing.ts/usePricingCalculator 买卖解耦试算、
  主站后台弹窗改「收号压价」价格语义文案、分销后台 SiteSettings 同步
- 测试：单测锚定 R=43 时 cost_delta=3 → 收号 217.4 / 卖价 263.2 不变 / markup 池 30.6→54.9

frontend/src/features/admin/api/adminDistribution.ts

@@ -13,6 +13,7 @@ export interface DistributionSite {
   settlement_hold_days: number
   listing_qrcode_url?: string
   receive_ratio_delta?: number
+  receive_cost_delta?: number
   created_at: string
 }
 
@@ -154,6 +155,7 @@ export async function updateDistributionSite(
       | 'settlement_hold_days'
       | 'listing_qrcode_url'
       | 'receive_ratio_delta'
+      | 'receive_cost_delta'
     >
   >
 ) {

frontend/src/features/admin/views/AdminDistributionSitesView.vue

@@ -59,7 +59,7 @@ const receiveRatioSubmitting = ref(false)
 const receiveRatioForm = reactive({
   site_id: 0,
   site_name: '',
-  receive_ratio_delta: 0,
+  receive_cost_delta: 0,
 })
 
 const qrDialogVisible = ref(false)
@@ -136,7 +136,7 @@ async function handleSettlementSubmit() {
 function handleOpenReceiveRatio(row: DistributionSite) {
   receiveRatioForm.site_id = row.id
   receiveRatioForm.site_name = row.site_name
-  receiveRatioForm.receive_ratio_delta = Number(row.receive_ratio_delta || 0)
+  receiveRatioForm.receive_cost_delta = Number(row.receive_cost_delta || 0)
   receiveRatioDialogVisible.value = true
 }
 
@@ -144,9 +144,9 @@ async function handleReceiveRatioSubmit() {
   receiveRatioSubmitting.value = true
   try {
     await updateDistributionSite(receiveRatioForm.site_id, {
-      receive_ratio_delta: Number(receiveRatioForm.receive_ratio_delta),
+      receive_cost_delta: Number(receiveRatioForm.receive_cost_delta),
     })
-    ElMessage.success(`【${receiveRatioForm.site_name}】收号比例下调已更新`)
+    ElMessage.success(`【${receiveRatioForm.site_name}】收号压价已更新`)
     receiveRatioDialogVisible.value = false
     await loadSites()
   } catch (err) {
@@ -530,15 +530,15 @@ onMounted(() => {
             </el-tag>
           </template>
         </el-table-column>
-        <el-table-column label="收号下调" width="110">
+        <el-table-column label="收号压价" width="110">
           <template #default="{ row }">
             <el-tag
-              :type="Number(row.receive_ratio_delta || 0) > 0 ? 'warning' : 'info'"
+              :type="Number(row.receive_cost_delta || 0) > 0 ? 'warning' : 'info'"
               size="small"
             >
               {{
-                Number(row.receive_ratio_delta || 0) > 0
-                  ? `-${Number(row.receive_ratio_delta).toFixed(1)} 点`
+                Number(row.receive_cost_delta || 0) > 0
+                  ? `低 ${Number(row.receive_cost_delta).toFixed(1)} 点`
                   : '与主站一致'
               }}
             </el-tag>
@@ -758,10 +758,10 @@ onMounted(() => {
       </template>
     </el-dialog>
 
-    <!-- 分站收号比例（主站为上限） -->
+    <!-- 分站收号压价（收号价始终不高于主站参考价） -->
     <el-dialog
       v-model="receiveRatioDialogVisible"
-      title="分站收号比例"
+      title="分站收号压价"
       width="520px"
       destroy-on-close
     >
@@ -769,16 +769,16 @@ onMounted(() => {
         type="info"
         :closable="false"
         show-icon
-        title="主站回收比例是上限。下调点数越大，号主底价越高、分站利润空间越大，但不能高于主站比例。0 表示与主站一致。"
+        title="分站收号价比主站更低：压价点数越大，号主在分站拿到的收号价越低。买家售价保持与主站一致，压价差进入三方分成（35% 收号 / 40% 卖出 / 25% 服务费）。0 表示与主站同价收号。"
         style="margin-bottom: 16px"
       />
       <el-form label-width="110px">
         <el-form-item label="分销站点">
           <el-input :model-value="receiveRatioForm.site_name" disabled />
         </el-form-item>
-        <el-form-item label="相对主站下调">
+        <el-form-item label="收号价比主站低">
           <el-input-number
-            v-model="receiveRatioForm.receive_ratio_delta"
+            v-model="receiveRatioForm.receive_cost_delta"
             :min="0"
             :max="20"
             :step="0.1"

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

@@ -58,6 +58,7 @@ export function usePublishForm(options: UsePublishFormOptions) {
   const siteStore = useDistributionSiteStore()
   const isDistribution = computed(() => siteStore.isDistribution)
   const receiveRatioDelta = computed(() => Number(siteStore.receiveRatioDelta || 0))
+  const receiveCostDelta = computed(() => Number(siteStore.receiveCostDelta || 0))
   const loading = ref(false)
   const uploading = ref(false)
   const suppressDraftSave = ref(false)
@@ -95,6 +96,7 @@ export function usePublishForm(options: UsePublishFormOptions) {
     selectedSkins,
     isDistribution,
     receiveRatioDelta,
+    receiveCostDelta,
   })
 
   // ========== 上号方式互斥 ==========