feat(monitor): admin channel monitor MVP with SSRF protection and batch aggregation

新增 admin「渠道监控」模块（参考 BingZi-233/check-cx），独立于现有 Channel 体系。
admin 配置 + 后台定时调用上游 LLM chat completions 健康检查 + 所有登录用户只读可见。

后端：
- ent: channel_monitor + channel_monitor_history（AES-256-GCM 加密 api_key）
- service 按职责拆分：service/aggregator/validate/checker/runner/ssrf
- provider strategy map 替代 switch（openai/anthropic/gemini）
- repository batch 聚合（ListLatestForMonitorIDs + ComputeAvailabilityForMonitors）消除 N+1
- runner: ticker(5s) + pond worker pool(5) + inFlight 防并发 + TrySubmit 防雪崩
  + 凌晨 3 点 cron 清理 30 天历史
- SSRF 防护：强制 https + 私网/loopback/云元数据 IP 拒绝（127/8、10/8、172.16/12、
  192.168/16、169.254/16、100.64/10、::1、fc00::/7、fe80::/10）+ DialContext
  在 socket 层防 DNS rebinding
- API key sanitize：擦除 url.Error 与上游响应 body 中的 sk-/sk-ant-/AIza/JWT 模式
- APIKeyDecryptFailed 标志位 + 单 monitor 路径检测，避免空 key 调用上游

handler:
- admin: CRUD + 手动触发 + 历史接口（api_key 脱敏）
- user: 只读列表 + 状态详情（去除 api_key/endpoint）
- ParseChannelMonitorID 共用 + dto.ChannelMonitorExtraModelStatus 共用

前端：
- 路由 /admin/channels/{pricing,monitor} + /monitor（用户只读）
- AppSidebar 父项 expandOnly 支持
- ChannelMonitorView 拆为 8 个子组件 + ChannelStatusView 拆出 detail dialog
- composables/useChannelMonitorFormat + constants/channelMonitor 共享
- i18n monitorCommon namespace 消除 admin/user 两 view 重复

合规：所有文件符合 CLAUDE.md（Go ≤ 500 行 / Vue ≤ 300 行 / 函数 ≤ 30 行）
CI: go build / gofmt / golangci-lint(0 issues) / make test-unit / pnpm build 全绿

frontend/src/components/user/MonitorDetailDialog.vue

@@ -0,0 +1,114 @@
+<template>
+  <BaseDialog
+    :show="show"
+    :title="title"
+    width="wide"
+    @close="$emit('close')"
+  >
+    <div v-if="loading" class="py-8 text-center text-sm text-gray-500">
+      {{ t('common.loading') }}
+    </div>
+    <div v-else-if="!detail" class="py-8 text-center text-sm text-gray-500">
+      {{ t('channelStatus.detailLoadError') }}
+    </div>
+    <div v-else class="overflow-x-auto">
+      <table class="w-full text-left text-sm">
+        <thead class="border-b border-gray-200 dark:border-dark-700">
+          <tr class="text-xs uppercase tracking-wider text-gray-500 dark:text-gray-400">
+            <th class="py-2 pr-3">{{ t('channelStatus.detailColumns.model') }}</th>
+            <th class="py-2 pr-3">{{ t('channelStatus.detailColumns.latestStatus') }}</th>
+            <th class="py-2 pr-3">{{ t('channelStatus.detailColumns.latestLatency') }}</th>
+            <th class="py-2 pr-3">{{ t('channelStatus.detailColumns.availability7d') }}</th>
+            <th class="py-2 pr-3">{{ t('channelStatus.detailColumns.availability15d') }}</th>
+            <th class="py-2 pr-3">{{ t('channelStatus.detailColumns.availability30d') }}</th>
+            <th class="py-2 pr-3">{{ t('channelStatus.detailColumns.avgLatency7d') }}</th>
+          </tr>
+        </thead>
+        <tbody>
+          <tr
+            v-for="m in detail.models"
+            :key="m.model"
+            class="border-b border-gray-100 dark:border-dark-800"
+          >
+            <td class="py-2 pr-3 font-medium text-gray-900 dark:text-gray-100">{{ m.model }}</td>
+            <td class="py-2 pr-3">
+              <span
+                class="inline-flex items-center rounded-full px-2 py-0.5 text-[11px]"
+                :class="statusBadgeClass(m.latest_status)"
+              >
+                {{ statusLabel(m.latest_status) }}
+              </span>
+            </td>
+            <td class="py-2 pr-3 text-gray-700 dark:text-gray-300">{{ formatLatency(m.latest_latency_ms) }}</td>
+            <td class="py-2 pr-3 text-gray-700 dark:text-gray-300">{{ formatPercent(m.availability_7d) }}</td>
+            <td class="py-2 pr-3 text-gray-700 dark:text-gray-300">{{ formatPercent(m.availability_15d) }}</td>
+            <td class="py-2 pr-3 text-gray-700 dark:text-gray-300">{{ formatPercent(m.availability_30d) }}</td>
+            <td class="py-2 pr-3 text-gray-700 dark:text-gray-300">{{ formatLatency(m.avg_latency_7d_ms) }}</td>
+          </tr>
+        </tbody>
+      </table>
+    </div>
+
+    <template #footer>
+      <div class="flex justify-end">
+        <button @click="$emit('close')" class="btn btn-secondary">
+          {{ t('channelStatus.closeDetail') }}
+        </button>
+      </div>
+    </template>
+  </BaseDialog>
+</template>
+
+<script setup lang="ts">
+import { ref, watch } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { useAppStore } from '@/stores/app'
+import { extractApiErrorMessage } from '@/utils/apiError'
+import {
+  status as fetchChannelMonitorDetail,
+  type UserMonitorDetail,
+} from '@/api/channelMonitor'
+import BaseDialog from '@/components/common/BaseDialog.vue'
+import { useChannelMonitorFormat } from '@/composables/useChannelMonitorFormat'
+
+const props = defineProps<{
+  show: boolean
+  monitorId: number | null
+  title: string
+}>()
+
+defineEmits<{
+  (e: 'close'): void
+}>()
+
+const { t } = useI18n()
+const appStore = useAppStore()
+const { statusLabel, statusBadgeClass, formatLatency, formatPercent } = useChannelMonitorFormat()
+
+const detail = ref<UserMonitorDetail | null>(null)
+const loading = ref(false)
+
+async function load(id: number) {
+  detail.value = null
+  loading.value = true
+  try {
+    detail.value = await fetchChannelMonitorDetail(id)
+  } catch (err: unknown) {
+    appStore.showError(extractApiErrorMessage(err, t('channelStatus.detailLoadError')))
+  } finally {
+    loading.value = false
+  }
+}
+
+watch(
+  () => [props.show, props.monitorId] as const,
+  ([show, id]) => {
+    if (!show) {
+      detail.value = null
+      return
+    }
+    if (id != null) void load(id)
+  },
+  { immediate: true },
+)
+</script>

frontend/src/components/user/MonitorPrimaryModelCell.vue

@@ -0,0 +1,71 @@
+<template>
+  <div class="flex items-center gap-2">
+    <span class="text-sm text-gray-900 dark:text-gray-100">{{ row.primary_model }}</span>
+    <HelpTooltip>
+      <template #trigger>
+        <span
+          class="inline-flex items-center rounded-full px-2 py-0.5 text-[11px] font-medium"
+          :class="statusBadgeClass(row.primary_status)"
+        >
+          {{ statusLabel(row.primary_status) }}
+        </span>
+      </template>
+      <div class="space-y-2">
+        <div class="text-xs font-semibold text-gray-100">
+          {{ row.primary_model }}
+          <span
+            class="ml-1 inline-flex items-center rounded-full px-1.5 py-0.5 text-[10px] font-medium"
+            :class="statusBadgeClass(row.primary_status)"
+          >
+            {{ statusLabel(row.primary_status) }}
+          </span>
+        </div>
+        <div v-if="(row.extra_models?.length ?? 0) === 0" class="text-[11px] text-gray-300">
+          {{ t('monitorCommon.extraModelsEmpty') }}
+        </div>
+        <div v-else class="space-y-1">
+          <div class="text-[11px] font-semibold uppercase tracking-wide text-gray-400">
+            {{ t('monitorCommon.extraModelsHeader') }}
+          </div>
+          <table class="w-full text-left text-[11px]">
+            <thead>
+              <tr class="text-gray-400">
+                <th class="py-0.5 pr-2 font-medium">{{ t('channelStatus.detailColumns.model') }}</th>
+                <th class="py-0.5 pr-2 font-medium">{{ t('channelStatus.detailColumns.latestStatus') }}</th>
+                <th class="py-0.5 font-medium">{{ t('channelStatus.detailColumns.latestLatency') }}</th>
+              </tr>
+            </thead>
+            <tbody>
+              <tr v-for="m in row.extra_models" :key="m.model">
+                <td class="py-0.5 pr-2 text-gray-100">{{ m.model }}</td>
+                <td class="py-0.5 pr-2">
+                  <span
+                    class="inline-flex items-center rounded-full px-1.5 py-0.5 text-[10px]"
+                    :class="statusBadgeClass(m.status)"
+                  >
+                    {{ statusLabel(m.status) }}
+                  </span>
+                </td>
+                <td class="py-0.5 text-gray-100">{{ formatLatency(m.latency_ms) }}</td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+      </div>
+    </HelpTooltip>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { useI18n } from 'vue-i18n'
+import type { UserMonitorView } from '@/api/channelMonitor'
+import HelpTooltip from '@/components/common/HelpTooltip.vue'
+import { useChannelMonitorFormat } from '@/composables/useChannelMonitorFormat'
+
+defineProps<{
+  row: UserMonitorView
+}>()
+
+const { t } = useI18n()
+const { statusLabel, statusBadgeClass, formatLatency } = useChannelMonitorFormat()
+</script>