Add id "/" and lang "de" fields to manifest.json. Add display_override with window-controls-overlay/standalone options and prefer_related_applications:false. Replace single media-mark.svg icon with 192x192 and 512x512 sized variants (media-mark-192.svg, media-mark-512.svg) containing gradient background, yellow strokes, and green circle with glow filter. Update service worker cache to v3 with scope "/" parameter
