feat: healthcheck backend and fix data types

also small various features

frontend/layouts/default.vue

@@ -31,8 +31,8 @@
         </NuxtLink>
       </nav>
 
-      <!-- Status indicator -->
-      <div class="px-4 py-4 border-t border-gray-800">
+      <!-- Status indicators -->
+      <div class="px-4 py-4 border-t border-gray-800 space-y-2">
         <div class="flex items-center gap-2">
           <span
             class="w-2 h-2 rounded-full shrink-0"
@@ -42,6 +42,15 @@
             {{ captureRunning ? 'Захват активен' : 'Захват остановлен' }}
           </span>
         </div>
+        <div class="flex items-center gap-2">
+          <span
+            class="w-2 h-2 rounded-full shrink-0"
+            :class="isOnline ? 'bg-green-400' : 'bg-red-500 animate-pulse'"
+          />
+          <span class="text-xs" :class="isOnline ? 'text-gray-400' : 'text-red-400'">
+            {{ isOnline ? 'Бэкенд онлайн' : 'Бэкенд недоступен' }}
+          </span>
+        </div>
       </div>
     </aside>
 
@@ -71,6 +80,15 @@
         </UButton>
       </header>
 
+      <!-- Offline banner -->
+      <div
+        v-if="!isOnline"
+        class="mx-6 mt-4 flex items-center gap-2 text-xs text-yellow-300 bg-yellow-950/50 border border-yellow-800/60 rounded-lg px-3 py-2 shrink-0"
+      >
+        <UIcon name="i-heroicons-signal-slash" class="w-4 h-4 shrink-0" />
+        Бэкенд недоступен — отображаются данные из БД
+      </div>
+
       <!-- Page content -->
       <main class="flex-1 overflow-auto p-6">
         <slot />
@@ -82,6 +100,7 @@
 <script setup lang="ts">
 const route = useRoute()
 const { status, stopCapture } = useCaptureStatus()
+const { isOnline } = useBackendStatus()
 
 const captureRunning = computed(() => status.value?.running ?? false)