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/shared/app-icon.tsx

@@ -0,0 +1,70 @@
+// components/shared/app-icon.tsx
+// Scrum4Me app icon — concept 5 (Rocket)
+// Gebruik: <AppIcon size={32} /> of <AppIcon size={64} className="..." />
+
+interface AppIconProps {
+  size?: number
+  className?: string
+}
+
+export function AppIcon({ size = 32, className }: AppIconProps) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 512 512"
+      fill="none"
+      xmlns="http://www.w3.org/2000/svg"
+      className={className}
+      aria-label="Scrum4Me"
+    >
+      <defs>
+        <linearGradient id="s4m-bg" x1="0" y1="0" x2="512" y2="512" gradientUnits="userSpaceOnUse">
+          <stop offset="0%" stopColor="#1a1028"/>
+          <stop offset="100%" stopColor="#0d0a14"/>
+        </linearGradient>
+        <linearGradient id="s4m-nose" x1="256" y1="60" x2="256" y2="212" gradientUnits="userSpaceOnUse">
+          <stop offset="0%" stopColor="#c4b5fd"/>
+          <stop offset="100%" stopColor="#7c3aed"/>
+        </linearGradient>
+      </defs>
+
+      {/* Background */}
+      <rect width="512" height="512" rx="114" fill="url(#s4m-bg)"/>
+
+      {/* Block 1 — PBI */}
+      <rect x="174" y="372" width="164" height="60" rx="12" fill="#4f6ef7" opacity="0.6"/>
+
+      {/* Block 2 — Story */}
+      <rect x="144" y="292" width="224" height="76" rx="12" fill="#6366f1" opacity="0.75"/>
+
+      {/* Block 3 — Task */}
+      <rect x="160" y="212" width="192" height="76" rx="12" fill="#7c3aed" opacity="0.9"/>
+
+      {/* Rocket nose */}
+      <path
+        d="M256 60 C222 60 160 122 160 212 H352 C352 122 290 60 256 60Z"
+        fill="url(#s4m-nose)"
+      />
+
+      {/* Window */}
+      <circle cx="256" cy="152" r="30" fill="#0d0a14" opacity="0.5"/>
+      <circle cx="256" cy="152" r="20" fill="#ede9fe" opacity="0.95"/>
+      <circle cx="248" cy="144" r="6" fill="white" opacity="0.5"/>
+
+      {/* Fins */}
+      <path d="M160 332 L108 400 L160 400 Z" fill="#4f6ef7" opacity="0.55"/>
+      <path d="M352 332 L404 400 L352 400 Z" fill="#4f6ef7" opacity="0.55"/>
+
+      {/* Flame */}
+      <path
+        d="M212 432 Q244 472 256 456 Q268 472 300 432"
+        stroke="#f59e0b" strokeWidth="12" strokeLinecap="round" fill="none" opacity="0.95"
+      />
+      <path
+        d="M232 432 Q248 460 256 448 Q264 460 280 432"
+        stroke="#fef3c7" strokeWidth="7" strokeLinecap="round" fill="none" opacity="0.7"
+      />
+    </svg>
+  )
+}