test: add attestation proof order rejection fixture

[latifkasuli]

Summary

• Add a verify_signatures tamper case that swaps the first two body attestations and re-signs only the proposer.
• Add an Lstar fixture vector that rejects a block whose body attestation order no longer matches the merged Type-2 proof component order.

Why

This pins the block-level proof ordering invariant without adding runtime/debug machinery: the proposer signature remains valid for the received block, while the attestation proof components are deliberately paired with the wrong body messages.

Validation

• uv run --group lint ruff check --no-fix --show-fixes
• uv run --group lint ruff format --check
• uv run --group lint ty check
• codespell via codespell_lib entrypoint, because this checkout's console-script shebang is stale
• uv run --group docs python -m mdformat --check docs/
• uv lock --check
• uv run --group test python -m pytest tests -n auto --maxprocesses=10 --durations=10 --dist=worksteal
• uv run --group test fill --fork=Lstar --clean --output /tmp/leanspec-full-consensus-fill tests/consensus -q

[latifkasuli]

CI note: the only failing check is Tests - Python 3.12 on macos-latest.

It failed before tests ran while building lean-multisig-py, due to DNS resolution for crates.io:

Could not resolve host: static.crates.io
failed to download https://static.crates.io/crates/itoa/1.0.18/download

All other checks are green, including fixture fill, interop, coverage, lint/format, and the Python 3.12/3.13/3.14 test jobs on the other runners. I do not have repository permissions to rerun the failed job, so this needs a maintainer rerun.