fix(engine): skip the legality clone for self-sacrifice mana costs - #7558

Investigator 3 of 3 reviewed 33 PRs for matthewevans. Five PRs had full patches adversarially reviewed as clean (engine fixes, parser updates, WASM serialization, and regression tests for the phase-rs/phase MTG engine). Five PRs had preview/truncated patches with no visible red flags. Twenty-three PRs were metadata-only and could not be patch-reviewed. The contributor is a MEMBER with focused single-repo activity. No malicious signals were found in any reviewable patch, but the shard lacks patch-level coverage for the majority of assigned PRs, preventing a confident safety determination.