Fix PWA install: static manifest.json + proper SVG icon

- Replace blob: manifest (ignored by Chrome) with static manifest.json
- Replace data: URL icon with real icon.svg file
- Link manifest and apple-touch-icon directly in <head>
- Remove blob/data URL generation from app.js

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

index.html

@@ -7,6 +7,8 @@
 <meta name="apple-mobile-web-app-capable" content="yes">
 <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
 <meta name="apple-mobile-web-app-title" content="NovaSonic">
+<link rel="manifest" href="manifest.json">
+<link rel="apple-touch-icon" href="icon.svg">
 <title>NovaSonic</title>
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link href="https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@300;400;500&display=swap" rel="stylesheet">