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/account/AccountActionMenu.vue

@@ -0,0 +1,21 @@
+<template>
+  <Teleport to="body">
+    <div v-if="show && position" class="action-menu-content fixed z-[9999] w-52 overflow-hidden rounded-xl bg-white shadow-lg ring-1 ring-black/5 dark:bg-dark-800" :style="{ top: position.top + 'px', left: position.left + 'px' }">
+      <div class="py-1">
+        <template v-if="account">
+          <button @click="$emit('test', account); $emit('close')" class="flex w-full items-center gap-2 px-4 py-2 text-sm hover:bg-gray-100"><span class="text-green-500">▶</span> {{ t('admin.accounts.testConnection') }}</button>
+          <button @click="$emit('stats', account); $emit('close')" class="flex w-full items-center gap-2 px-4 py-2 text-sm hover:bg-gray-100"><span class="text-indigo-500">📊</span> {{ t('admin.accounts.viewStats') }}</button>
+          <template v-if="account.type === 'oauth' || account.type === 'setup-token'">
+            <button @click="$emit('reauth', account); $emit('close')" class="flex w-full items-center gap-2 px-4 py-2 text-sm hover:bg-gray-100 text-blue-600">🔗 {{ t('admin.accounts.reAuthorize') }}</button>
+            <button @click="$emit('refresh-token', account); $emit('close')" class="flex w-full items-center gap-2 px-4 py-2 text-sm hover:bg-gray-100 text-purple-600">🔄 {{ t('admin.accounts.refreshToken') }}</button>
+          </template>
+        </template>
+      </div>
+    </div>
+  </Teleport>
+</template>
+
+<script setup lang="ts">
+import { useI18n } from 'vue-i18n'
+defineProps(['show', 'account', 'position']); defineEmits(['close', 'test', 'stats', 'reauth', 'refresh-token']); const { t } = useI18n()
+</script>