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>

manifest.json

@@ -0,0 +1,25 @@
+{
+  "name": "NovaSonic",
+  "short_name": "NovaSonic",
+  "description": "Self-hosted music streaming PWA",
+  "start_url": "/",
+  "scope": "/",
+  "display": "standalone",
+  "orientation": "portrait-primary",
+  "background_color": "#07070f",
+  "theme_color": "#07070f",
+  "icons": [
+    {
+      "src": "icon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "any"
+    },
+    {
+      "src": "icon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "maskable"
+    }
+  ]
+}