Add Next.js web app

Feed with live updates and pinning, profiles with follow/pin, featured song
picker, settings for all music services, and account deletion.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/web/next.config.ts

@@ -0,0 +1,7 @@
+import type { NextConfig } from 'next';
+
+const config: NextConfig = {
+  transpilePackages: ['@musicshare/shared'],
+};
+
+export default config;