Add tools/check-no-gdscript-sim-logic.py and wire it as verify step 18 (TOTAL
20→21). Fails if presentation GDScript (src/game/engine/src/**/*.gd) re-introduces
catalog yield aggregation (`yield_production += …`) or hand-built spec dicts
(`"yield_production": …`) — the exact drift class just moved to Rust. Verified to
flag the pre-7e2baa25d aggregation and pass clean on the current tree. Logic
belongs in the mc-* crates, reached via the GDExtension bridge (Rail 1).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
