refactor(frontend): comprehensive split of large view files into modular components

- Split UsersView.vue into UserCreateModal, UserEditModal, UserApiKeysModal, etc.
- Split UsageView.vue into UsageStatsCards, UsageFilters, UsageTable, etc.
- Split DashboardView.vue into UserDashboardStats, UserDashboardCharts, etc.
- Split AccountsView.vue into AccountTableActions, AccountTableFilters, etc.
- Standardized TypeScript types across new components to resolve implicit 'any' and 'never[]' errors.
- Improved overall frontend maintainability and code clarity.

frontend/src/components/admin/user/UserApiKeysModal.vue

@@ -0,0 +1,47 @@
+<template>
+  <BaseDialog :show="show" :title="t('admin.users.userApiKeys')" width="wide" @close="$emit('close')">
+    <div v-if="user" class="space-y-4">
+      <div class="flex items-center gap-3 rounded-xl bg-gray-50 p-4 dark:bg-dark-700">
+        <div class="flex h-10 w-10 items-center justify-center rounded-full bg-primary-100 dark:bg-primary-900/30">
+          <span class="text-lg font-medium text-primary-700 dark:text-primary-300">{{ user.email.charAt(0).toUpperCase() }}</span>
+        </div>
+        <div><p class="font-medium text-gray-900 dark:text-white">{{ user.email }}</p><p class="text-sm text-gray-500 dark:text-dark-400">{{ user.username }}</p></div>
+      </div>
+      <div v-if="loading" class="flex justify-center py-8"><svg class="h-8 w-8 animate-spin text-primary-500" fill="none" viewBox="0 0 24 24"><circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4"></circle><path class="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"></path></svg></div>
+      <div v-else-if="apiKeys.length === 0" class="py-8 text-center"><p class="text-sm text-gray-500">{{ t('admin.users.noApiKeys') }}</p></div>
+      <div v-else class="max-h-96 space-y-3 overflow-y-auto">
+        <div v-for="key in apiKeys" :key="key.id" class="rounded-xl border border-gray-200 bg-white p-4 dark:border-dark-600 dark:bg-dark-800">
+          <div class="flex items-start justify-between">
+            <div class="min-w-0 flex-1">
+              <div class="mb-1 flex items-center gap-2"><span class="font-medium text-gray-900 dark:text-white">{{ key.name }}</span><span :class="['badge text-xs', key.status === 'active' ? 'badge-success' : 'badge-danger']">{{ key.status }}</span></div>
+              <p class="truncate font-mono text-sm text-gray-500">{{ key.key.substring(0, 20) }}...{{ key.key.substring(key.key.length - 8) }}</p>
+            </div>
+          </div>
+          <div class="mt-3 flex flex-wrap gap-4 text-xs text-gray-500">
+            <div class="flex items-center gap-1"><span>{{ t('admin.users.group') }}: {{ key.group?.name || t('admin.users.none') }}</span></div>
+            <div class="flex items-center gap-1"><span>{{ t('admin.users.columns.created') }}: {{ formatDateTime(key.created_at) }}</span></div>
+          </div>
+        </div>
+      </div>
+    </div>
+  </BaseDialog>
+</template>
+
+<script setup lang="ts">
+import { ref, watch } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { adminAPI } from '@/api/admin'
+import { formatDateTime } from '@/utils/format'
+import type { User, ApiKey } from '@/types'
+import BaseDialog from '@/components/common/BaseDialog.vue'
+
+const props = defineProps<{ show: boolean, user: User | null }>()
+defineEmits(['close']); const { t } = useI18n()
+const apiKeys = ref<ApiKey[]>([]); const loading = ref(false)
+
+watch(() => props.show, (v) => { if (v && props.user) load() })
+const load = async () => {
+  if (!props.user) return; loading.value = true
+  try { const res = await adminAPI.users.getUserApiKeys(props.user.id); apiKeys.value = res.items || [] } catch {} finally { loading.value = false }
+}
+</script>