fix: harden session settle and close access-key flows

[brendanjryan]

Summary

• validate session settle/close senders against the channel payee with operation-specific errors
• use the raw Tempo transaction path for non-fee-payer settle/close and wait for confirmed success before mutating local state
• add access-key settle/close regressions plus a sessionManager.close HTTP failure test

[pkg-pr-new]

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npm i https://pkg.pr.new/mppx@340

commit: f4ff319