feat: ST-101-ST-110 M1 producten, PBI backlog, iconen en PWA manifest

- Product aanmaken/bewerken/archiveren/herstellen (ST-101, ST-103)
- SplitPane component met versleepbare splitter en localStorage (ST-104)
- PanelNavBar herbruikbaar paneelheader component (ST-105)
- PbiList met prioriteitsgroepen, inline aanmaken, filter en verwijderen (ST-106-ST-110)
- StoryPanel placeholder rechter paneel met selectie via Zustand (ST-109)
- App iconen geinstalleerd: favicon, apple-icon, PWA manifest (192/512px)
- AppIcon SVG component in navigatiebar
- Root layout metadata bijgewerkt naar Nederlands

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

components/products/archive-product-button.tsx

@@ -0,0 +1,54 @@
+'use client'
+
+import { useState, useTransition } from 'react'
+import { Button } from '@/components/ui/button'
+import { archiveProductAction } from '@/actions/products'
+
+interface ArchiveProductButtonProps {
+  productId: string
+}
+
+export function ArchiveProductButton({ productId }: ArchiveProductButtonProps) {
+  const [confirming, setConfirming] = useState(false)
+  const [isPending, startTransition] = useTransition()
+
+  function handleArchive() {
+    startTransition(async () => {
+      await archiveProductAction(productId)
+    })
+  }
+
+  if (confirming) {
+    return (
+      <div className="flex gap-2 shrink-0">
+        <Button
+          variant="destructive"
+          size="sm"
+          disabled={isPending}
+          onClick={handleArchive}
+        >
+          {isPending ? 'Bezig…' : 'Ja, archiveer'}
+        </Button>
+        <Button
+          variant="ghost"
+          size="sm"
+          onClick={() => setConfirming(false)}
+          disabled={isPending}
+        >
+          Annuleren
+        </Button>
+      </div>
+    )
+  }
+
+  return (
+    <Button
+      variant="outline"
+      size="sm"
+      className="shrink-0 border-error/40 text-error hover:bg-error/10"
+      onClick={() => setConfirming(true)}
+    >
+      Archiveren
+    </Button>
+  )
+}