add endpoints plugin with fleet list view and monitoring drafts

Server-side RMM telemetry plugin: current-snapshot endpointstates plus append-only curated endpointevents, resolved to existing Computer assets by hostname. Adds ADR-010 asset panels (status, services, recent events), dashboard quiet and stability cards, and a minimal Fleet list view that links into existing PC detail pages. Registers the activity sidebar icon and a dev-only sample seeder. Ingest arrives on the generic collector route; the future C# agent design record lives in docs/DESIGN-DECISIONS-agent.md.

frontend/src/views/AppLayout.vue

@@ -109,7 +109,7 @@ import ToastHost from '../components/ToastHost.vue'
 import {
   Sun, Moon, LayoutDashboard, Calendar, Map, Cog, Monitor,
   Printer, Globe, Usb, AppWindow, BookOpen, BarChart3, Bell, Image, ShieldCheck, Ruler,
-  Box, KeyRound, LogOut, Wrench
+  Box, KeyRound, LogOut, Wrench, Activity
 } from 'lucide-vue-next'
 import { useAuthStore } from '../stores/auth'
 import { currentTheme, toggleTheme } from '../stores/theme'
@@ -178,6 +178,7 @@ const iconMap = {
   'ruler': Ruler,
   'box': Box,
   'wrench': Wrench,
+  'activity': Activity,
 }
 
 // Default navigation (used as fallback if API fails)