refactor: replace SVG icons with PNG format in manifest and update apple-touch-icon reference

Replace media-mark-192.svg/media-mark-512.svg with .png equivalents in manifest.json icon entries and update image/svg+xml to image/png MIME types. Add media-mark-192.png and media-mark-512.png binary assets. Update sw.js SHELL array to cache .png files instead of .svg. Change apple-touch-icon href from media-mark.svg to media-mark-192.png in index.html head

static/manifest.json

@@ -13,8 +13,8 @@
   "theme_color": "#1f252d",
   "orientation": "any",
   "icons": [
-    {"src": "/static/media-mark-192.svg", "sizes": "192x192", "type": "image/svg+xml", "purpose": "any"},
-    {"src": "/static/media-mark-512.svg", "sizes": "512x512", "type": "image/svg+xml", "purpose": "any"},
-    {"src": "/static/media-mark-512.svg", "sizes": "512x512", "type": "image/svg+xml", "purpose": "maskable"}
+    {"src": "/static/media-mark-192.png", "sizes": "192x192", "type": "image/png", "purpose": "any"},
+    {"src": "/static/media-mark-512.png", "sizes": "512x512", "type": "image/png", "purpose": "any"},
+    {"src": "/static/media-mark-512.png", "sizes": "512x512", "type": "image/png", "purpose": "maskable"}
   ]
 }

static/sw.js

@@ -1,5 +1,5 @@
 const CACHE_NAME = 'media-max-shell-v5';
-const SHELL = ['/static/media-mark.svg', '/static/media-mark-192.svg', '/static/media-mark-512.svg', '/static/manifest.json'];
+const SHELL = ['/static/media-mark.svg', '/static/media-mark-192.png', '/static/media-mark-512.png', '/static/manifest.json'];
 
 self.addEventListener('install', event => {
   event.waitUntil(caches.open(CACHE_NAME).then(cache => cache.addAll(SHELL)));