feat(widgets): voeg relativeTime toe in lib/utils, expiringWarning-badge in CaddyWidget

- relativeTime(date: Date) helper toegevoegd aan lib/utils.ts
- AuditWidget gebruikt nu gedeelde relativeTime in plaats van inline functie
- CaddyWidget toont rode badge als soonest cert-expiry <30 dagen
- app/page.tsx berekent expiringWarning voor CaddyInitial

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

app/_components/AuditWidget.tsx

@@ -3,6 +3,7 @@
 import { useCallback, useEffect, useState } from 'react'
 import Link from 'next/link'
 import { apiFetch } from '@/lib/csrf'
+import { relativeTime } from '@/lib/utils'
 
 type LatestRun = { id: string; flow_key: string; status: string; started_at: string }
 export type AuditInitial =
@@ -17,16 +18,6 @@ const STATUS_STYLES: Record<string, string> = {
   cancelled: 'bg-zinc-100 text-zinc-600 dark:bg-zinc-800 dark:text-zinc-400',
 }
 
-function relativeTime(isoString: string): string {
-  const diff = Date.now() - new Date(isoString).getTime()
-  const minutes = Math.floor(diff / 60_000)
-  if (minutes < 1) return 'zojuist'
-  if (minutes < 60) return `${minutes}m geleden`
-  const hours = Math.floor(minutes / 60)
-  if (hours < 24) return `${hours}u geleden`
-  return `${Math.floor(hours / 24)}d geleden`
-}
-
 async function fetchLatestRun(): Promise<LatestRun | null> {
   const res = await apiFetch('/api/audit/latest')
   if (!res.ok) throw new Error(`${res.status}`)
@@ -66,7 +57,7 @@ export default function AuditWidget({ initial }: { initial: AuditInitial }) {
             >
               {data.status}
             </span>
-            <span className="text-xs text-muted-foreground">{relativeTime(data.started_at)}</span>
+            <span className="text-xs text-muted-foreground">{relativeTime(new Date(data.started_at))}</span>
           </div>
           <p className="font-mono text-xs text-muted-foreground truncate">{data.flow_key}</p>
         </div>