feat: SIWX

[ftheirs]

Backend and SDK modifications to support CAIP-122 (SIWX)
Update demo-app to allow the user to use either SIWE or SIWX authentication

⚠️ Breaking Changes ⚠️

• Short description

  Domain extraction is now automatic from URIs, and session providers are optional when creating MspClient instances.

• Who is affected

  • Backend API consumers calling /auth/nonce or /auth/message that previously provided a domain field
  • SDK users calling MspClient.auth.SIWE() or MspClient.auth.SIWX() with a domain parameter
  • SDK users creating MspClient instances with a required sessionProvider parameter

• Suggested code changes

  Backend API: Remove domain field from NonceRequest payloads. The backend extracts the domain from the uri field.

SDK - SIWE/SIWX: Remove the domain parameter

  // Before
  await mspClient.auth.SIWE(walletClient, "localhost:3000", "http://localhost:3000");
  

  // After
  await mspClient.auth.SIWE(walletClient, "http://localhost:3000");

SDK - MspClient: sessionProvider is now optional. You can set it after authentication:

  // Before
  const client = await MspClient.connect(config, sessionProvider);
 

  // After
  const client = await MspClient.connect(config);
  // ... authenticate ...
  client.setSessionProvider(async () => session);