Fix Amplify environment variable configuration

- Add amplify.yml for proper build configuration
- Update next.config.ts to expose YOUTUBE_API_KEY env var
- This should fix the issue with secrets not being available in production

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

next.config.ts

@@ -24,6 +24,9 @@ const nextConfig: NextConfig = {
       },
     ],
   },
+  env: {
+    YOUTUBE_API_KEY: process.env.YOUTUBE_API_KEY || '',
+  },
 };
 
 export default nextConfig;