Default ProofArgs.suppress_proof to true. With it false, the receiver's
`contract sign` unconditionally built an invoice promise, but the sender
address is never plumbed through, so a bare send/receive failed with
NoSenderAddressProvided (#729). The CLI never sets this field, so every
default `contract sign --receive` hit the broken path; the basic tests
passed only because they set suppress_proof = true by hand.
Drop those workarounds from contract_srs/contract_rsr so they now exercise
the default path, and opt the proof-using tests (contract_early_proofs_srs,
contract_early_proofs_rsr, contract_accounts) into proofs explicitly.
jwinterm