feat: host inventory (agent.inventory), host detail page, UI columns

Store hardware/software snapshots on hosts; warn on hardware changes. Host card from Hosts list. Add agent version column to Events/Overview; rename Hosts table columns and sort by status.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/AppSidebar.vue

@@ -47,7 +47,7 @@ const navItems = computed(() => {
     { to: "/events", label: "События", icon: "☰", match: "prefix" as const },
     { to: "/reports", label: "Отчёты", icon: "▤", match: "prefix" as const },
     { to: "/problems", label: "Проблемы", icon: "!", match: "prefix" as const },
-    { to: "/hosts", label: "Хосты", icon: "⬢", match: "exact" as const },
+    { to: "/hosts", label: "Хосты", icon: "⬢", match: "prefix" as const },
   ];
   if (isAdmin()) {
     items.push(