feat(health): add model and provider health monitoring

- Rename the original health monitor to endpoint health monitor
- Add tab navigation for endpoint, model, and provider health views
- Add model health monitor cards with availability, latency, first-byte latency, and 60-point history
- Add admin-only provider health monitor with collapsible active-provider sections
- Show per-provider model health cards after expanding a provider
- Add backend model health and provider health monitor payload builders
- Add admin endpoint for provider health monitoring
- Add provider-scoped usage breakdown filtering for per-provider model statistics
- Add frontend API types and request helpers for model/provider health data
- Add demo mock data for model and provider health monitoring
- Fix model health timeline time-unit handling so request history segments render correctly

Verification:
- cargo fmt
- npm run type-check
- npm run build
- cargo test -p aether-gateway health_models
- cargo test -p aether-gateway health_providers
- cargo test -p aether-gateway gateway_exposes_frontdoor_manifest_without_proxying_upstream

frontend/src/views/shared/HealthMonitor.vue

@@ -1,18 +1,69 @@
 <template>
   <div class="space-y-6 pb-8">
-    <HealthMonitorCard
-      title="健康监控"
-      :is-admin="isAdminPage"
-      :show-provider-info="isAdminPage"
-    />
+    <Tabs v-model="activeTab">
+      <TabsList
+        class="tabs-button-list grid w-full"
+        :class="isAdminPage ? 'max-w-2xl grid-cols-3' : 'max-w-md grid-cols-2'"
+      >
+        <TabsTrigger value="endpoint">
+          端点健康监控
+        </TabsTrigger>
+        <TabsTrigger value="model">
+          模型健康监控
+        </TabsTrigger>
+        <TabsTrigger
+          v-if="isAdminPage"
+          value="provider"
+        >
+          提供商健康监控
+        </TabsTrigger>
+      </TabsList>
+
+      <TabsContent
+        value="endpoint"
+        class="mt-4"
+      >
+        <HealthMonitorCard
+          title="端点健康监控"
+          :is-admin="isAdminPage"
+          :show-provider-info="isAdminPage"
+        />
+      </TabsContent>
+
+      <TabsContent
+        value="model"
+        class="mt-4"
+      >
+        <ModelHealthMonitorCard
+          title="模型健康监控"
+          :is-admin="isAdminPage"
+          :show-provider-info="isAdminPage"
+        />
+      </TabsContent>
+
+      <TabsContent
+        v-if="isAdminPage"
+        value="provider"
+        class="mt-4"
+      >
+        <ProviderHealthMonitorCard title="提供商健康监控" />
+      </TabsContent>
+    </Tabs>
   </div>
 </template>
 
 <script setup lang="ts">
-import { computed } from 'vue'
+import { computed, ref } from 'vue'
 import { useRoute } from 'vue-router'
+import Tabs from '@/components/ui/tabs.vue'
+import TabsContent from '@/components/ui/tabs-content.vue'
+import TabsList from '@/components/ui/tabs-list.vue'
+import TabsTrigger from '@/components/ui/tabs-trigger.vue'
 import HealthMonitorCard from '@/features/providers/components/HealthMonitorCard.vue'
+import ModelHealthMonitorCard from '@/features/providers/components/ModelHealthMonitorCard.vue'
+import ProviderHealthMonitorCard from '@/features/providers/components/ProviderHealthMonitorCard.vue'
 
 const route = useRoute()
 const isAdminPage = computed(() => route.path.startsWith('/admin'))
+const activeTab = ref('endpoint')
 </script>