feat(ui): add delivery records tab to service management

Management.vue gains a second tab listing MySQL delivery tasks from the backend (search, status filter, detail dialog, one-time credential reveal with copy/download). components.d.ts regenerated for the new Element Plus components.

Also add narrow-viewport (<=760px) style tweaks to AppHeader/AppMain/DefaultLayout; these are partial small-screen optimizations, not a full mobile adaptation.

frontend/src/layouts/DefaultLayout.vue

@@ -19,4 +19,15 @@ import AppMain from '@/components/Layout/AppMain.vue'
   grid-template-rows: 70px 1fr;
   height: 100vh;
 }
+
+@media (max-width: 760px) {
+  .shell {
+    grid-template-columns: minmax(0, 1fr);
+    grid-template-rows: 58px minmax(0, 1fr);
+  }
+
+  .shell :deep(.sidebar) {
+    display: none;
+  }
+}
 </style>