fix(usage): 用户使用记录不下发账号计费倍率

- 将 usage log DTO 拆分为用户/管理员两类
- 用户接口不返回 account_rate_multiplier/ip_address/account
- 管理员接口保留管理员字段
- 补充契约测试防止回归

frontend/src/views/admin/UsageView.vue

@@ -42,11 +42,11 @@ import UsageStatsCards from '@/components/admin/usage/UsageStatsCards.vue'; impo
 import UsageTable from '@/components/admin/usage/UsageTable.vue'; import UsageExportProgress from '@/components/admin/usage/UsageExportProgress.vue'
 import UsageCleanupDialog from '@/components/admin/usage/UsageCleanupDialog.vue'
 import ModelDistributionChart from '@/components/charts/ModelDistributionChart.vue'; import TokenUsageTrend from '@/components/charts/TokenUsageTrend.vue'
-import type { UsageLog, TrendDataPoint, ModelStat } from '@/types'; import type { AdminUsageStatsResponse, AdminUsageQueryParams } from '@/api/admin/usage'
+import type { AdminUsageLog, TrendDataPoint, ModelStat } from '@/types'; import type { AdminUsageStatsResponse, AdminUsageQueryParams } from '@/api/admin/usage'
 
 const { t } = useI18n()
 const appStore = useAppStore()
-const usageStats = ref<AdminUsageStatsResponse | null>(null); const usageLogs = ref<UsageLog[]>([]); const loading = ref(false); const exporting = ref(false)
+const usageStats = ref<AdminUsageStatsResponse | null>(null); const usageLogs = ref<AdminUsageLog[]>([]); const loading = ref(false); const exporting = ref(false)
 const trendData = ref<TrendDataPoint[]>([]); const modelStats = ref<ModelStat[]>([]); const chartsLoading = ref(false); const granularity = ref<'day' | 'hour'>('day')
 let abortController: AbortController | null = null; let exportAbortController: AbortController | null = null
 const exportProgress = reactive({ show: false, progress: 0, current: 0, total: 0, estimatedTime: '' })
@@ -92,7 +92,7 @@ const exportToExcel = async () => {
   if (exporting.value) return; exporting.value = true; exportProgress.show = true
   const c = new AbortController(); exportAbortController = c
   try {
-    const all: UsageLog[] = []; let p = 1; let total = pagination.total
+    const all: AdminUsageLog[] = []; let p = 1; let total = pagination.total
     while (true) {
       const res = await adminUsageAPI.list({ page: p, page_size: 100, ...filters.value }, { signal: c.signal })
       if (c.signal.aborted) break; if (p === 1) { total = res.total; exportProgress.total = total }