feat: add system metrics dashboard with resource monitoring

- Add system metrics endpoint (CPU load, memory, swap, network traffic)
- Collect metrics from /proc and /sys (no subprocess required)
- Overhaul dashboard to pull from per-subsystem models
- Remove deprecated /status/all monolithic endpoint
- Improve networkd import to handle optional priority prefix
- Fix CSS duplicate .grid-4 rule and unused dashboard imports

webui/static/app.js

@@ -1,6 +1,6 @@
-import { h, render, Link, hComp, ToastContainer, connect, apiFetch, modelRegister, modelFetch, reactive } from '/static/hoover/index.js?v=8';
+import { h, render, Link, hComp, ToastContainer, connect, apiFetch, modelRegister, modelFetch, reactive } from '/static/hoover/index.js?v=10';
 
-import DashboardPage from '/static/pages/dashboard.js?v=9';
+import DashboardPage from '/static/pages/dashboard.js?v=11';
 import InterfacesPage from '/static/pages/interfaces.js?v=9';
 import ZonesPage from '/static/pages/zones.js?v=9';
 import RulesPage from '/static/pages/rules.js?v=9';
@@ -28,16 +28,6 @@ const Nav = [
     { path: '/logs',       label: 'Logs'       },
 ];
 
-/* ── Model registration ────────────────────────────────────── */
-modelRegister('status', {
-    subsystem: 'status',
-    fetch: async () => {
-        const r = await apiFetch('/api/status/all');
-        if (!r.ok) throw new Error(r.error);
-        return r.data;
-    },
-});
-
 modelRegister('firewall', {
     subsystem: 'firewall',
     fetch: async () => {
@@ -166,8 +156,26 @@ modelRegister('logs', {
     },
 });
 
+modelRegister('status', {
+    subsystem: '*',
+    fetch: async () => {
+        const [pendingR, metricsR] = await Promise.allSettled([
+            apiFetch('/api/status/pending'),
+            apiFetch('/api/status/system-metrics'),
+        ]);
+        const result = {};
+        if (pendingR.status === 'fulfilled' && pendingR.value.ok) {
+            result.pending = pendingR.value.data || {};
+        }
+        if (metricsR.status === 'fulfilled' && metricsR.value.ok) {
+            result.metrics = metricsR.value.data || {};
+        }
+        return result;
+    },
+});
+
 /* ── Initial fetch ─────────────────────────────────────────── */
-for (const name of ['status', 'firewall', 'network', 'dnsmasq', 'nginx', 'backends', 'wireguard', 'acme']) {
+for (const name of ['firewall', 'network', 'dnsmasq', 'nginx', 'backends', 'wireguard', 'acme', 'status']) {
     modelFetch(name);
 }
 modelFetch('logs', 'journal');