feat(dashboard): vervang SECTIONS-grid door 5 live status-widgets

Parallel server-side fetches via Promise.allSettled voor Docker, Caddy,
systemd, Git en Audit. Iedere widget toont geaggregeerde status en
refresht elke 30s client-side onafhankelijk van de andere widgets.

- lib/agent-fetch.ts: gedeelde client-side streaming helper
- app/api/audit/latest/route.ts: GET endpoint voor AuditWidget refresh
- app/_components/DockerWidget.tsx: running/total containers
- app/_components/CaddyWidget.tsx: soonest cert expiry in dagen
- app/_components/SystemdWidget.tsx: healthy/total units (of niet geconfigureerd)
- app/_components/GitWidget.tsx: dirty repo count (of niet geconfigureerd)
- app/_components/AuditWidget.tsx: laatste FlowRun status + relatief tijdstip
- app/page.tsx: vervangt SECTIONS-grid, doet parallel fetches, rendert widgets

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/agent-fetch.ts

@@ -0,0 +1,41 @@
+import { apiFetch } from '@/lib/csrf'
+
+export async function fetchAgentOutput(commandKey: string, args: string[] = []): Promise<string> {
+  const res = await apiFetch('/api/agent/exec', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ command_key: commandKey, args }),
+  })
+
+  if (!res.ok) {
+    const text = await res.text()
+    throw new Error(`agent ${res.status}: ${text}`)
+  }
+
+  const reader = res.body?.getReader()
+  if (!reader) throw new Error('no response body')
+
+  const decoder = new TextDecoder()
+  let buffer = ''
+  let output = ''
+
+  while (true) {
+    const { done, value } = await reader.read()
+    if (done) break
+    buffer += decoder.decode(value, { stream: true })
+    const lines = buffer.split('\n')
+    buffer = lines.pop() ?? ''
+    for (const line of lines) {
+      if (line.startsWith('data:')) {
+        try {
+          const parsed = JSON.parse(line.slice(5).trim()) as { data?: string }
+          if (parsed.data !== undefined) output += parsed.data
+        } catch {
+          // ignore malformed SSE
+        }
+      }
+    }
+  }
+
+  return output
+}