Add favicon images and web manifest for site branding

- Added favicon-16x16.png, favicon-32x32.png, and favicon.ico to enhance site identity across platforms.
- Introduced site.webmanifest to define application metadata, including icons and color themes for a better user experience on mobile devices.

data/html/site.webmanifest

@@ -0,0 +1,19 @@
+{
+  "name": "Black Hole Share",
+  "short_name": "BHS",
+  "icons": [
+    {
+      "src": "/android-chrome-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "/android-chrome-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ],
+  "theme_color": "#000000",
+  "background_color": "#000000",
+  "display": "standalone"
+}