feat(channel): 渠道管理全链路集成 — 模型映射、定价、限制、用量统计

- 渠道模型映射：支持精确匹配和通配符映射，按平台隔离
- 渠道模型定价：支持 token/按次/图片三种计费模式，区间分层定价
- 模型限制：渠道可限制仅允许定价列表中的模型
- 计费模型来源：支持 requested/upstream 两种计费模型选择
- 用量统计：usage_logs 新增 channel_id/model_mapping_chain/billing_tier/billing_mode 字段
- Dashboard 支持 model_source 维度（requested/upstream/mapping）查看模型统计
- 全部 gateway handler 统一接入 ResolveChannelMappingAndRestrict
- 修复测试：同步 SoraGenerationRepository 接口、SQL INSERT 参数、scan 字段

frontend/src/views/admin/UsageView.vue

@@ -34,6 +34,7 @@
             :show-metric-toggle="true"
             :start-date="startDate"
             :end-date="endDate"
+            :filters="breakdownFilters"
           />
           <GroupDistributionChart
             v-model:metric="groupDistributionMetric"
@@ -42,6 +43,7 @@
             :show-metric-toggle="true"
             :start-date="startDate"
             :end-date="endDate"
+            :filters="breakdownFilters"
           />
         </div>
         <div class="grid grid-cols-1 gap-6 lg:grid-cols-2">
@@ -57,6 +59,7 @@
             :title="t('usage.endpointDistribution')"
             :start-date="startDate"
             :end-date="endDate"
+            :filters="breakdownFilters"
           />
           <TokenUsageTrend :trend-data="trendData" :loading="chartsLoading" />
         </div>
@@ -169,6 +172,17 @@ const cleanupDialogVisible = ref(false)
 const showBalanceHistoryModal = ref(false)
 const balanceHistoryUser = ref<AdminUser | null>(null)
 
+const breakdownFilters = computed(() => {
+  const f: Record<string, any> = {}
+  if (filters.value.user_id) f.user_id = filters.value.user_id
+  if (filters.value.api_key_id) f.api_key_id = filters.value.api_key_id
+  if (filters.value.account_id) f.account_id = filters.value.account_id
+  if (filters.value.group_id) f.group_id = filters.value.group_id
+  if (filters.value.request_type != null) f.request_type = filters.value.request_type
+  if (filters.value.billing_type != null) f.billing_type = filters.value.billing_type
+  return f
+})
+
 const handleUserClick = async (userId: number) => {
   try {
     const user = await adminAPI.users.getById(userId)