fix: frontend build error

frontend/src/views/user/UsageView.vue

@@ -246,7 +246,7 @@ import EmptyState from '@/components/common/EmptyState.vue'
 import Select from '@/components/common/Select.vue'
 import DateRangePicker from '@/components/common/DateRangePicker.vue'
 import type { UsageLog, ApiKey, UsageQueryParams, UsageStatsResponse } from '@/types'
-import type { Column } from '@/components/common/DataTable.vue'
+import type { Column } from '@/components/common/types'
 
 const { t } = useI18n()
 const appStore = useAppStore()
@@ -316,21 +316,6 @@ const pagination = ref({
   pages: 0
 })
 
-const totalTokens = computed(() => {
-  return usageLogs.value.reduce((sum, log) =>
-    sum + log.input_tokens + log.output_tokens, 0
-  )
-})
-
-const totalCost = computed(() => {
-  return usageLogs.value.reduce((sum, log) => sum + log.total_cost, 0)
-})
-
-const avgDuration = computed(() => {
-  if (usageLogs.value.length === 0) return 0
-  return usageLogs.value.reduce((sum, log) => sum + log.duration_ms, 0) / usageLogs.value.length
-})
-
 const formatDuration = (ms: number): string => {
   if (ms < 1000) return `${ms.toFixed(0)}ms`
   return `${(ms / 1000).toFixed(2)}s`