test: cover merge continuity snapshot fields

[AztecBot]

Summary

The tx-merge and block-merge validators compare full tree snapshots and state references, but the local negative tests only covered a subset of those fields. This adds focused regression coverage for the missing snapshot indices and state fields so a future refactor cannot silently narrow continuity checks.

Fix

• Add tx-merge negative tests for note hash, nullifier, and public data tree snapshot index mismatches.
• Add block-merge negative tests for L1-to-L2 index, note hash index, nullifier root/index, and public data root/index mismatches.

Testing

• PATH=/home/aztec-dev/aztec-packages/noir/noir-repo/target/debug:$PATH nargo test --package rollup_lib non_consecutive_note_hash_tree_next_available_leaf_index non_consecutive_nullifier_tree_next_available_leaf_index non_consecutive_public_data_tree_next_available_leaf_index non_consecutive_l1_to_l2_message_tree_next_available_leaf_index non_consecutive_nullifier_tree_roots non_consecutive_public_data_tree_roots --silence-warnings

Issues

• Closes AztecProtocol/aztec-claude#1613 — merge continuity tests miss snapshot index and state-field negative coverage

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Created by claudebox · group: rollup-audit-remediation