feat: enhance PWA manifest with multi-size icons, window controls overlay, and German locale settings

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

static/manifest.json

@@ -1,14 +1,19 @@
 {
   "name": "Media Max",
   "short_name": "Media Max",
+  "id": "/",
+  "lang": "de",
   "description": "Media Max: Radarr, Sonarr und SABnzbd im Überblick",
   "start_url": "/",
   "scope": "/",
   "display": "standalone",
+  "display_override": ["window-controls-overlay", "standalone"],
+  "prefer_related_applications": false,
   "background_color": "#151619",
   "theme_color": "#1f252d",
   "orientation": "any",
   "icons": [
-    {"src": "/static/media-mark.svg", "sizes": "any", "type": "image/svg+xml", "purpose": "any maskable"}
+    {"src": "/static/media-mark-192.svg", "sizes": "192x192", "type": "image/svg+xml", "purpose": "any maskable"},
+    {"src": "/static/media-mark-512.svg", "sizes": "512x512", "type": "image/svg+xml", "purpose": "any maskable"}
   ]
 }

static/media-mark-192.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" width="512" height="512"><defs><linearGradient id="bg" x1="0" y1="0" x2="1" y2="1"><stop offset="0" stop-color="#293542"/><stop offset="1" stop-color="#15191f"/></linearGradient><filter id="glow"><feGaussianBlur stdDeviation="2.2" result="b"/><feMerge><feMergeNode in="b"/><feMergeNode in="SourceGraphic"/></feMerge></filter></defs><rect x="5" y="5" width="54" height="54" rx="15" fill="url(#bg)" stroke="#60a9e6" stroke-width="2.5"/><path d="M17 21h30M17 31h19M17 41h30" fill="none" stroke="#f4c430" stroke-width="4" stroke-linecap="round"/><circle cx="46" cy="31" r="7" fill="#159447" stroke="#c9ffe0" stroke-width="2" filter="url(#glow)"/></svg>

static/media-mark-512.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" width="512" height="512"><defs><linearGradient id="bg" x1="0" y1="0" x2="1" y2="1"><stop offset="0" stop-color="#293542"/><stop offset="1" stop-color="#15191f"/></linearGradient><filter id="glow"><feGaussianBlur stdDeviation="2.2" result="b"/><feMerge><feMergeNode in="b"/><feMergeNode in="SourceGraphic"/></feMerge></filter></defs><rect x="5" y="5" width="54" height="54" rx="15" fill="url(#bg)" stroke="#60a9e6" stroke-width="2.5"/><path d="M17 21h30M17 31h19M17 41h30" fill="none" stroke="#f4c430" stroke-width="4" stroke-linecap="round"/><circle cx="46" cy="31" r="7" fill="#159447" stroke="#c9ffe0" stroke-width="2" filter="url(#glow)"/></svg>

static/sw.js

@@ -1,4 +1,4 @@
-const CACHE_NAME = 'media-max-shell-v2';
+const CACHE_NAME = 'media-max-shell-v3';
 const SHELL = ['/static/media-mark.svg', '/static/manifest.json'];
 
 self.addEventListener('install', event => {