feat: add SVG icon and generate PNG icons

- Added a new SVG icon file for the application.
- Created a manifest.json file for the web app with relevant metadata.
- Introduced package-lock.json to manage dependencies.
- Implemented a script to generate PNG icons from the SVG source using sharp.

manifest.json

@@ -0,0 +1,29 @@
+{
+  "name": "Finger Chooser",
+  "short_name": "Finger Chooser",
+  "description": "Lege mehrere Finger auf das Display – einer wird zufällig ausgewählt.",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#0c0c14",
+  "theme_color": "#0c0c14",
+  "lang": "de",
+  "orientation": "portrait-primary",
+  "icons": [
+    {
+      "src": "icons/icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "icons/icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    },
+    {
+      "src": "icons/icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "maskable"
+    }
+  ]
+}