fix(bytecode): exclude MLOAD from modifies_memory and update test

[GarmashAlex]

• MLOAD only reads from memory; it does not write to it. Including it in OpCode::modifies_memory misclassifies read-only behavior as memory-modifying.
• Memory expansion (zero-filling) during reads is an allocation side effect, not a semantic write by the opcode itself. This aligns with interpreter implementations and EVM references.
• Updated the test to expect false for MLOAD, kept MSTORE as modifying, and ADD as non-modifying.
• This improves correctness for analyzers/inspectors relying on opcode classification and keeps consistency with other read-only ops (e.g., KECCAK256, RETURN) that also expand memory but aren’t flagged as modifying.

[codspeed-hq]

CodSpeed Performance Report

Merging #3004 will not alter performance

_{Comparing GarmashAlex:fix/opcode-modifies-memory-mload (880725a) with main (0fc5a4b)}

Summary

✅ 173 untouched

[rakita]

True mload does not change the memory.