feat(solana): KKSOLSW1 lookup-table account attestation tests

[BitHighlander]

Four tests for the transaction-bound attestation that upgrades an ALT transaction from a blind sign to a described one.

The positive test asserts the screen count, not just that signing succeeded — and that is the whole reason it was worth writing: it caught a real firmware bug on first run. nanopb hands each repeated bytes element back as a {size, bytes[32]} struct, and the firmware was casting the array to (uint8_t(*)[32]) — hashing the size word plus 28 bytes of the first key. The signature never verified. A test that only checked "did it sign" would have passed, because the fallback path signs perfectly well.

test	asserts
..._shown_and_blind_sign_still_follows	base flow + 1 identity + 1 per account, baseline codes still at the tail
..._bad_signature_degrades_to_todays_flow	unverifiable attestation adds nothing, refuses nothing
..._does_not_replay_onto_another_transaction	same signature on a perturbed tx describes nothing
..._no_signer_loaded_means_no_extra_screens	trust is opt-in per session

Note for whoever extends these: the three negative cases pass trivially if the signer is not loaded, because "no extra screens" is also what a broken positive path produces. Only the count assertion distinguishes them. That is why it exists and why it should not be relaxed into "signature is 64 bytes".

messages_solana_pb2.py regenerated — must use a protoc whose output protobuf==3.20.3 accepts; system protoc emits google.protobuf.runtime_version imports that 3.20 lacks. grpcio-tools==1.48.2 works.