Add PWA support for install-to-home-screen

Adds manifest.json, service worker with static asset caching,
resized cat icons, and meta tags for iOS/Android installability.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

raggr-frontend/rsbuild.config.ts

@@ -4,7 +4,16 @@ import { pluginReact } from '@rsbuild/plugin-react';
 export default defineConfig({
   plugins: [pluginReact()],
   html: {
-    title: 'Raggr',
+    title: 'Ask Simba',
     favicon: './src/assets/favicon.svg',
+    tags: [
+      { tag: 'link', attrs: { rel: 'manifest', href: '/manifest.json' } },
+      { tag: 'meta', attrs: { name: 'theme-color', content: '#2A4D38' } },
+      { tag: 'link', attrs: { rel: 'apple-touch-icon', href: '/apple-touch-icon.png' } },
+      { tag: 'meta', attrs: { name: 'apple-mobile-web-app-capable', content: 'yes' } },
+    ],
+  },
+  output: {
+    copy: [{ from: './public', to: '.' }],
   },
 });