WIP: add Qwen3.5 Megatron reference receipts

[zrr1999]

Status

Work-in-progress native ms-swift/Megatron reference and receipt path for Qwen3.5 raw bit-exact alignment.

The Torch reference is deterministic, but cross-framework text loss is still 0/10 exact.

Scope

• local/eager accuracy-compatible model path
• compile-disabled determinism
• native first-step/internal boundary receipts
• Qwen3.5 argument and callback integration

Validation

• formal Torch world4 EP4 CUDA/BF16 10-step transaction: same-side raw exact x3
• local path contains zero TransformerEngine modules

Not ready for merge; cross-framework forward/loss, backward, optimizer, checkpoint, and multimodal gates remain open.