feat(observability): phase 8 - container stats, notifications & dashboard

Add container monitoring and notification system:
- Docker Stats API: real-time CPU/memory for running containers
- Webhook notifications for errors (deploy failures, stale, proxy unhealthy)
- Event log auto-pruning (daily, 30-day retention)
- ContainerStats component with auto-polling progress bars
- SystemHealthCard dashboard widget with running/proxy/error counts
- Full EN/RU i18n for stats and system health

web/src/routes/+page.svelte

@@ -4,6 +4,7 @@
 	import ProjectCard from '$lib/components/ProjectCard.svelte';
 	import SkeletonCard from '$lib/components/SkeletonCard.svelte';
 	import EmptyState from '$lib/components/EmptyState.svelte';
+	import SystemHealthCard from '$lib/components/SystemHealthCard.svelte';
 	import { IconDeploy, IconBox, IconServer, IconAlert, IconClock } from '$lib/components/icons';
 	import { t } from '$lib/i18n';
 
@@ -124,6 +125,9 @@
 		</a>
 	</div>
 
+	<!-- System health summary -->
+	<SystemHealthCard />
+
 	<!-- Project cards -->
 	<div>
 		<h2 class="text-lg font-semibold text-[var(--text-primary)]">{$t('dashboard.projects')}</h2>