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/user/profile/ProfileEditForm.vue

+<template>
+  <div class="card">
+    <div class="border-b border-gray-100 px-6 py-4 dark:border-dark-700">
+      <h2 class="text-lg font-medium text-gray-900 dark:text-white">
+        {{ t('profile.editProfile') }}
+      </h2>
+    </div>
+    <div class="px-6 py-6">
+      <form @submit.prevent="handleUpdateProfile" class="space-y-4">
+        <div>
+          <label for="username" class="input-label">
+            {{ t('profile.username') }}
+          </label>
+          <input
+            id="username"
+            v-model="username"
+            type="text"
+            class="input"
+            :placeholder="t('profile.enterUsername')"
+          />
+        </div>
+
+        <div class="flex justify-end pt-4">
+          <button type="submit" :disabled="loading" class="btn btn-primary">
+            {{ loading ? t('profile.updating') : t('profile.updateProfile') }}
+          </button>
+        </div>
+      </form>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { ref, watch } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { useAuthStore } from '@/stores/auth'
+import { useAppStore } from '@/stores/app'
+import { userAPI } from '@/api'
+
+const props = defineProps<{
+  initialUsername: string
+}>()
+
+const { t } = useI18n()
+const authStore = useAuthStore()
+const appStore = useAppStore()
+
+const username = ref(props.initialUsername)
+const loading = ref(false)
+
+watch(() => props.initialUsername, (val) => {
+  username.value = val
+})
+
+const handleUpdateProfile = async () => {
+  if (!username.value.trim()) {
+    appStore.showError(t('profile.usernameRequired'))
+    return
+  }
+
+  loading.value = true
+  try {
+    const updatedUser = await userAPI.updateProfile({
+      username: username.value
+    })
+    authStore.user = updatedUser
+    appStore.showSuccess(t('profile.updateSuccess'))
+  } catch (error: any) {
+    appStore.showError(error.response?.data?.detail || t('profile.updateFailed'))
+  } finally {
+    loading.value = false
+  }
+}
+</script>

frontend/src/components/user/profile/ProfileInfoCard.vue

+<template>
+  <div class="card overflow-hidden">
+    <div
+      class="border-b border-gray-100 bg-gradient-to-r from-primary-500/10 to-primary-600/5 px-6 py-5 dark:border-dark-700 dark:from-primary-500/20 dark:to-primary-600/10"
+    >
+      <div class="flex items-center gap-4">
+        <!-- Avatar -->
+        <div
+          class="flex h-16 w-16 items-center justify-center rounded-2xl bg-gradient-to-br from-primary-500 to-primary-600 text-2xl font-bold text-white shadow-lg shadow-primary-500/20"
+        >
+          {{ user?.email?.charAt(0).toUpperCase() || 'U' }}
+        </div>
+        <div class="min-w-0 flex-1">
+          <h2 class="truncate text-lg font-semibold text-gray-900 dark:text-white">
+            {{ user?.email }}
+          </h2>
+          <div class="mt-1 flex items-center gap-2">
+            <span :class="['badge', user?.role === 'admin' ? 'badge-primary' : 'badge-gray']">
+              {{ user?.role === 'admin' ? t('profile.administrator') : t('profile.user') }}
+            </span>
+            <span
+              :class="['badge', user?.status === 'active' ? 'badge-success' : 'badge-danger']"
+            >
+              {{ user?.status }}
+            </span>
+          </div>
+        </div>
+      </div>
+    </div>
+    <div class="px-6 py-4">
+      <div class="space-y-3">
+        <div class="flex items-center gap-3 text-sm text-gray-600 dark:text-gray-400">
+          <svg
+            class="h-4 w-4 text-gray-400 dark:text-gray-500"
+            fill="none"
+            viewBox="0 0 24 24"
+            stroke="currentColor"
+            stroke-width="1.5"
+          >
+            <path
+              stroke-linecap="round"
+              stroke-linejoin="round"
+              d="M21.75 6.75v10.5a2.25 2.25 0 01-2.25 2.25h-15a2.25 2.25 0 01-2.25-2.25V6.75m19.5 0A2.25 2.25 0 0019.5 4.5h-15a2.25 2.25 0 00-2.25 2.25m19.5 0v.243a2.25 2.25 0 01-1.07 1.916l-7.5 4.615a2.25 2.25 0 01-2.36 0L3.32 8.91a2.25 2.25 0 01-1.07-1.916V6.75"
+            />
+          </svg>
+          <span class="truncate">{{ user?.email }}</span>
+        </div>
+        <div
+          v-if="user?.username"
+          class="flex items-center gap-3 text-sm text-gray-600 dark:text-gray-400"
+        >
+          <svg
+            class="h-4 w-4 text-gray-400 dark:text-gray-500"
+            fill="none"
+            viewBox="0 0 24 24"
+            stroke="currentColor"
+            stroke-width="1.5"
+          >
+            <path
+              stroke-linecap="round"
+              stroke-linejoin="round"
+              d="M15.75 6a3.75 3.75 0 11-7.5 0 3.75 3.75 0 017.5 0zM4.501 20.118a7.5 7.5 0 0114.998 0A17.933 17.933 0 0112 21.75c-2.676 0-5.216-.584-7.499-1.632z"
+            />
+          </svg>
+          <span class="truncate">{{ user.username }}</span>
+        </div>
+      </div>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { useI18n } from 'vue-i18n'
+import type { User } from '@/types'
+
+defineProps<{
+  user: User | null
+}>()
+
+const { t } = useI18n()
+</script>

frontend/src/components/user/profile/ProfilePasswordForm.vue

+<template>
+  <div class="card">
+    <div class="border-b border-gray-100 px-6 py-4 dark:border-dark-700">
+      <h2 class="text-lg font-medium text-gray-900 dark:text-white">
+        {{ t('profile.changePassword') }}
+      </h2>
+    </div>
+    <div class="px-6 py-6">
+      <form @submit.prevent="handleChangePassword" class="space-y-4">
+        <div>
+          <label for="old_password" class="input-label">
+            {{ t('profile.currentPassword') }}
+          </label>
+          <input
+            id="old_password"
+            v-model="form.old_password"
+            type="password"
+            required
+            autocomplete="current-password"
+            class="input"
+          />
+        </div>
+
+        <div>
+          <label for="new_password" class="input-label">
+            {{ t('profile.newPassword') }}
+          </label>
+          <input
+            id="new_password"
+            v-model="form.new_password"
+            type="password"
+            required
+            autocomplete="new-password"
+            class="input"
+          />
+          <p class="input-hint">
+            {{ t('profile.passwordHint') }}
+          </p>
+        </div>
+
+        <div>
+          <label for="confirm_password" class="input-label">
+            {{ t('profile.confirmNewPassword') }}
+          </label>
+          <input
+            id="confirm_password"
+            v-model="form.confirm_password"
+            type="password"
+            required
+            autocomplete="new-password"
+            class="input"
+          />
+          <p
+            v-if="form.new_password && form.confirm_password && form.new_password !== form.confirm_password"
+            class="input-error-text"
+          >
+            {{ t('profile.passwordsNotMatch') }}
+          </p>
+        </div>
+
+        <div class="flex justify-end pt-4">
+          <button type="submit" :disabled="loading" class="btn btn-primary">
+            {{ loading ? t('profile.changingPassword') : t('profile.changePasswordButton') }}
+          </button>
+        </div>
+      </form>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { ref } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { useAppStore } from '@/stores/app'
+import { userAPI } from '@/api'
+
+const { t } = useI18n()
+const appStore = useAppStore()
+
+const loading = ref(false)
+const form = ref({
+  old_password: '',
+  new_password: '',
+  confirm_password: ''
+})
+
+const handleChangePassword = async () => {
+  if (form.value.new_password !== form.value.confirm_password) {
+    appStore.showError(t('profile.passwordsNotMatch'))
+    return
+  }
+
+  if (form.value.new_password.length < 8) {
+    appStore.showError(t('profile.passwordTooShort'))
+    return
+  }
+
+  loading.value = true
+  try {
+    await userAPI.changePassword(form.value.old_password, form.value.new_password)
+    form.value = { old_password: '', new_password: '', confirm_password: '' }
+    appStore.showSuccess(t('profile.passwordChangeSuccess'))
+  } catch (error: any) {
+    appStore.showError(error.response?.data?.detail || t('profile.passwordChangeFailed'))
+  } finally {
+    loading.value = false
+  }
+}
+</script>

frontend/src/composables/useTableLoader.ts

+import { ref, reactive, onUnmounted } from 'vue'
+import { useDebounceFn } from '@vueuse/core'
+
+interface PaginationState {
+  page: number
+  page_size: number
+  total: number
+  pages: number
+}
+
+interface TableLoaderOptions<T, P> {
+  fetchFn: (page: number, pageSize: number, params: P, options?: { signal: AbortSignal }) => Promise<{
+    items: T[]
+    total: number
+    pages: number
+  }>
+  initialParams?: P
+  pageSize?: number
+  debounceMs?: number
+}
+
+export function useTableLoader<T, P extends Record<string, any>>(options: TableLoaderOptions<T, P>) {
+  const { fetchFn, initialParams, pageSize = 20, debounceMs = 300 } = options
+
+  const items = ref<T[]>([])
+  const loading = ref(false)
+  const params = reactive<P>({ ...(initialParams || {}) } as P)
+  const pagination = reactive<PaginationState>({
+    page: 1,
+    page_size: pageSize,
+    total: 0,
+    pages: 0
+  })
+
+  let abortController: AbortController | null = null
+
+  const isAbortError = (error: any) => {
+    return error?.name === 'AbortError' || error?.code === 'ERR_CANCELED'
+  }
+
+  const load = async () => {
+    if (abortController) {
+      abortController.abort()
+    }
+    abortController = new AbortController()
+    loading.value = true
+
+    try {
+      const response = await fetchFn(
+        pagination.page,
+        pagination.page_size,
+        params,
+        { signal: abortController.signal }
+      )
+      
+      items.value = response.items
+      pagination.total = response.total
+      pagination.pages = response.pages
+    } catch (error) {
+      if (!isAbortError(error)) {
+        throw error
+      }
+    } finally {
+      if (abortController?.signal.aborted === false) {
+        loading.value = false
+      }
+    }
+  }
+
+  const reload = () => {
+    pagination.page = 1
+    return load()
+  }
+
+  const debouncedLoad = useDebounceFn(reload, debounceMs)
+
+  const handlePageChange = (page: number) => {
+    pagination.page = page
+    load()
+  }
+
+  const handlePageSizeChange = (size: number) => {
+    pagination.page_size = size
+    reload()
+  }
+
+  onUnmounted(() => {
+    abortController?.abort()
+  })
+
+  return {
+    items,
+    loading,
+    params,
+    pagination,
+    load,
+    reload,
+    debouncedLoad,
+    handlePageChange,
+    handlePageSizeChange
+  }
+}