Connect your Tempo wallet (via passkey) and make paid requests using the Machine Payments Protocol.

The buyer UI lets you:

1. Connect an existing Tempo wallet using your passkey (biometric/PIN)
2. Make a paid request to an MPP-protected endpoint
3. See the 402 challenge → credential → receipt flow in action

Uses KeyManager.http('https://keys.tempo.xyz') so you can sign in from any device with your existing Tempo passkey.

Built with vtrr (SSR + client hydration), wagmi for wallet connection, and mppx/client for payment handling.