feat: support advertised tempo charge modes

[brendanjryan]

Summary

• add supportedModes to the Tempo charge request schema and serialize it into methodDetails
• negotiate client submission mode from the server-advertised modes while preserving the existing default preference order
• reject hash or transaction credentials on the server when the challenge did not advertise the corresponding mode

Context

This matches the Tempo charge spec update in tempoxyz/mpp-specs#243, where:

• pull maps to type="transaction" credentials
• push maps to type="hash" credentials
• omitting supportedModes means both modes are supported for back-compat

[pkg-pr-new]

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npm i https://pkg.pr.new/mppx@338

commit: fd4ae77