fix: resolve ERR_INSUFFICIENT_RESOURCES connection exhaustion

- Add concurrency limiter (max 4 GET requests) to API layer, leaving
  slots for SSE and health checks. Write ops bypass the limiter.
- Add AbortController to ContainerStats, project detail page, and
  dashboard to cancel in-flight requests on navigation/unmount.
- Move global SSE connection from layout to events page (only consumer).
- Add 30s heartbeat to SSE endpoint to detect zombie connections.
- Serialize dashboard project fetches to avoid parallel burst.
- Rebuild frontend in dev-server.sh so go:embed stays in sync.

web/src/routes/+layout.svelte

@@ -8,12 +8,9 @@
 	import LocaleSwitcher from '$lib/components/LocaleSwitcher.svelte';
 	import { IconDashboard, IconProjects, IconDeploy, IconEvents, IconWifi, IconSettings, IconMenu, IconX, IconLogout, IconGlobe } from '$lib/components/icons';
 	import { goto } from '$app/navigation';
-	import { connectGlobalEvents, type SSEConnection } from '$lib/sse';
-	import { instanceStatusStore } from '$lib/stores/instance-status';
 	import { resolvedTheme, applyTheme } from '$lib/stores/theme';
 	import { exchangeOidcToken, setAuthToken, clearAuth, isAuthenticated } from '$lib/auth';
 	import { logout as apiLogout, getHealth } from '$lib/api';
-	import { publishEventLog } from '$lib/stores/event-log-bus';
 	import type { DockerHealth, ProxyHealth } from '$lib/types';
 	import { t } from '$lib/i18n';
 
@@ -38,7 +35,6 @@
 		return pathname.startsWith(href);
 	}
 
-	let sseConnection: SSEConnection | null = null;
 	let sidebarOpen = $state(false);
 	let dockerHealth = $state<DockerHealth | null>(null);
 	let proxyHealth = $state<ProxyHealth | null>(null);
@@ -85,26 +81,13 @@
 		}
 	});
 
-	// Start SSE and health polling when authenticated.
+	// Start health polling when authenticated.
 	// Uses $effect to react to route changes (e.g., after login navigation).
 	$effect(() => {
 		void $page.url.pathname;
 
-		if (!isAuthenticated() || sseConnection) return;
+		if (!isAuthenticated() || healthInterval) return;
 
-		sseConnection = connectGlobalEvents({
-			onInstanceStatus(payload) {
-				instanceStatusStore.update(payload);
-			},
-			onDeployStatus(payload) {
-				instanceStatusStore.notifyDeploy(payload);
-			},
-			onEventLog(payload) {
-				publishEventLog(payload);
-			}
-		});
-
-		// Poll Docker health every 30s.
 		async function checkHealth() {
 			try {
 				const h = await getHealth();
@@ -121,8 +104,6 @@
 	});
 
 	onDestroy(() => {
-		sseConnection?.close();
-		sseConnection = null;
 		if (healthInterval) clearInterval(healthInterval);
 	});
 </script>