feat(announcements): add admin/user announcement system

Implements announcements end-to-end (admin CRUD + read status, user list + mark read) with OR-of-AND targeting. Also breaks the ent<->service import cycle by moving schema-facing constants/targeting into a new domain package.

frontend/src/components/admin/announcements/AnnouncementReadStatusDialog.vue

@@ -0,0 +1,186 @@
+<template>
+  <BaseDialog
+    :show="show"
+    :title="t('admin.announcements.readStatus')"
+    width="extra-wide"
+    @close="handleClose"
+  >
+    <div class="space-y-4">
+      <div class="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
+        <div class="flex-1">
+          <input
+            v-model="search"
+            type="text"
+            class="input"
+            :placeholder="t('admin.announcements.searchUsers')"
+            @input="handleSearch"
+          />
+        </div>
+        <button @click="load" :disabled="loading" class="btn btn-secondary" :title="t('common.refresh')">
+          <Icon name="refresh" size="md" :class="loading ? 'animate-spin' : ''" />
+        </button>
+      </div>
+
+      <DataTable :columns="columns" :data="items" :loading="loading">
+        <template #cell-email="{ value }">
+          <span class="font-medium text-gray-900 dark:text-white">{{ value }}</span>
+        </template>
+
+        <template #cell-balance="{ value }">
+          <span class="font-medium text-gray-900 dark:text-white">${{ Number(value ?? 0).toFixed(2) }}</span>
+        </template>
+
+        <template #cell-eligible="{ value }">
+          <span :class="['badge', value ? 'badge-success' : 'badge-gray']">
+            {{ value ? t('admin.announcements.eligible') : t('common.no') }}
+          </span>
+        </template>
+
+        <template #cell-read_at="{ value }">
+          <span class="text-sm text-gray-500 dark:text-dark-400">
+            {{ value ? formatDateTime(value) : t('admin.announcements.unread') }}
+          </span>
+        </template>
+      </DataTable>
+
+      <Pagination
+        v-if="pagination.total > 0"
+        :page="pagination.page"
+        :total="pagination.total"
+        :page-size="pagination.page_size"
+        @update:page="handlePageChange"
+        @update:pageSize="handlePageSizeChange"
+      />
+    </div>
+
+    <template #footer>
+      <div class="flex justify-end">
+        <button type="button" class="btn btn-secondary" @click="handleClose">{{ t('common.close') }}</button>
+      </div>
+    </template>
+  </BaseDialog>
+</template>
+
+<script setup lang="ts">
+import { computed, onMounted, reactive, ref, watch } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { useAppStore } from '@/stores/app'
+import { adminAPI } from '@/api/admin'
+import { formatDateTime } from '@/utils/format'
+import type { AnnouncementUserReadStatus } from '@/types'
+import type { Column } from '@/components/common/types'
+
+import BaseDialog from '@/components/common/BaseDialog.vue'
+import DataTable from '@/components/common/DataTable.vue'
+import Pagination from '@/components/common/Pagination.vue'
+import Icon from '@/components/icons/Icon.vue'
+
+const { t } = useI18n()
+const appStore = useAppStore()
+
+const props = defineProps<{
+  show: boolean
+  announcementId: number | null
+}>()
+
+const emit = defineEmits<{
+  (e: 'close'): void
+}>()
+
+const loading = ref(false)
+const search = ref('')
+
+const pagination = reactive({
+  page: 1,
+  page_size: 20,
+  total: 0,
+  pages: 0
+})
+
+const items = ref<AnnouncementUserReadStatus[]>([])
+
+const columns = computed<Column[]>(() => [
+  { key: 'email', label: t('common.email') },
+  { key: 'username', label: t('admin.users.columns.username') },
+  { key: 'balance', label: t('common.balance') },
+  { key: 'eligible', label: t('admin.announcements.eligible') },
+  { key: 'read_at', label: t('admin.announcements.readAt') }
+])
+
+let currentController: AbortController | null = null
+
+async function load() {
+  if (!props.show || !props.announcementId) return
+
+  if (currentController) currentController.abort()
+  currentController = new AbortController()
+
+  try {
+    loading.value = true
+    const res = await adminAPI.announcements.getReadStatus(
+      props.announcementId,
+      pagination.page,
+      pagination.page_size,
+      search.value
+    )
+
+    items.value = res.items
+    pagination.total = res.total
+    pagination.pages = res.pages
+    pagination.page = res.page
+    pagination.page_size = res.page_size
+  } catch (error: any) {
+    if (currentController.signal.aborted || error?.name === 'AbortError') return
+    console.error('Failed to load read status:', error)
+    appStore.showError(error.response?.data?.detail || t('admin.announcements.failedToLoadReadStatus'))
+  } finally {
+    loading.value = false
+  }
+}
+
+function handlePageChange(page: number) {
+  pagination.page = page
+  load()
+}
+
+function handlePageSizeChange(pageSize: number) {
+  pagination.page_size = pageSize
+  pagination.page = 1
+  load()
+}
+
+let searchDebounceTimer: number | null = null
+function handleSearch() {
+  if (searchDebounceTimer) window.clearTimeout(searchDebounceTimer)
+  searchDebounceTimer = window.setTimeout(() => {
+    pagination.page = 1
+    load()
+  }, 300)
+}
+
+function handleClose() {
+  emit('close')
+}
+
+watch(
+  () => props.show,
+  (v) => {
+    if (!v) return
+    pagination.page = 1
+    load()
+  }
+)
+
+watch(
+  () => props.announcementId,
+  () => {
+    if (!props.show) return
+    pagination.page = 1
+    load()
+  }
+)
+
+onMounted(() => {
+  // noop
+})
+</script>