Build deterministic model round-trip gates

Validate roundtrip model conversion against frozen reference

Validating refactors against frozen reference behavior (loss curves, outputs).

• · dir: string

• · bash/CLI
• · CUDA/FFI

• · Baseline/reference available
• · Git repo available
• · Test fixtures/seeding available

• · Verification step catches regression, halts pipeline
• · Non-deterministic output fails bit-identity gate

• · Independent verification phase before acceptance
• · Determinism/reproducibility gates
• · Reproducible test fixtures as reference
• · Frozen reference for regression detection