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.

scripts/generate-icons.js

@@ -0,0 +1,24 @@
+const sharp = require('sharp');
+const path = require('path');
+const fs = require('fs');
+
+const src = path.join(__dirname, '../icons/icon.svg');
+const out = path.join(__dirname, '../icons');
+
+const sizes = [
+  { name: 'apple-touch-icon.png', size: 180 },
+  { name: 'icon-192.png',         size: 192 },
+  { name: 'icon-512.png',         size: 512 },
+  { name: 'favicon-32.png',       size: 32  },
+];
+
+(async () => {
+  const svg = fs.readFileSync(src);
+  for (const { name, size } of sizes) {
+    await sharp(svg)
+      .resize(size, size)
+      .png()
+      .toFile(path.join(out, name));
+    console.log(`✓ ${name} (${size}×${size})`);
+  }
+})();