fix: frontend type definitions match actual backend API responses

- AlertsPage: template fields alert_type/value/is_recovery (was type/message/recovered)
- CommandsPage: remove non-existent is_dangerous/duration/admin_name; use admin_username
- ScriptsPage: ExecHistoryItem matches /scripts/executions response shape
- types/api.ts: CommandLogItem + SshSessionItem + ScriptExecItem aligned to backend
- Remove unused PaginatedResponse imports from CommandsPage/ScriptsPage

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/pages/AlertsPage.vue

@@ -60,12 +60,12 @@
         density="comfortable"
         @update:page="page = $event; loadAlerts()"
       >
-        <template #item.type="{ item }">
-          <v-chip :color="typeColor(item.type)" size="small" variant="tonal" label>
+        <template #item.alert_type="{ item }">
+          <v-chip :color="typeColor(item.alert_type)" size="small" variant="tonal" label>
             <template #prepend>
-              <v-icon size="12">{{ typeIcon(item.type) }}</v-icon>
+              <v-icon size="12">{{ typeIcon(item.alert_type) }}</v-icon>
             </template>
-            {{ item.type }}
+            {{ item.alert_type }}
           </v-chip>
         </template>
 
@@ -73,22 +73,18 @@
           <span class="font-weight-medium">{{ item.server_name }}</span>
         </template>
 
-        <template #item.message="{ item }">
-          <span class="text-body-2">{{ item.message }}</span>
+        <template #item.value="{ item }">
+          <span class="text-body-2">{{ item.value }}</span>
         </template>
 
-        <template #item.recovered="{ item }">
-          <v-chip v-if="item.recovered" color="success" size="small" variant="tonal" label>已恢复</v-chip>
+        <template #item.is_recovery="{ item }">
+          <v-chip v-if="item.is_recovery" color="success" size="small" variant="tonal" label>已恢复</v-chip>
           <v-chip v-else color="error" size="small" variant="tonal" label>告警中</v-chip>
         </template>
 
         <template #item.created_at="{ item }">
           <span class="text-caption text-medium-emphasis">{{ item.created_at }}</span>
         </template>
-
-        <template #item.recovered_at="{ item }">
-          <span class="text-caption text-medium-emphasis">{{ item.recovered_at || '—' }}</span>
-        </template>
         <template #no-data>
           <div class="text-center text-medium-emphasis py-6">暂无数据</div>
         </template>
@@ -133,12 +129,11 @@ const statusOptions = [
 ]
 
 const headers = [
-  { title: '类型', key: 'type', width: 100 },
+  { title: '类型', key: 'alert_type', width: 100 },
   { title: '服务器', key: 'server_name' },
-  { title: '消息', key: 'message' },
-  { title: '状态', key: 'recovered', width: 100 },
-  { title: '告警时间', key: 'created_at', width: 160 },
-  { title: '恢复时间', key: 'recovered_at', width: 160 },
+  { title: '详情', key: 'value' },
+  { title: '状态', key: 'is_recovery', width: 100 },
+  { title: '时间', key: 'created_at', width: 160 },
 ]
 
 // ── Data loading ──