Add transfer control-CFG (cfg for control inputs) + smoke-test coverage

[lfengad]

Summary

Ports the control-input CFG feature (from i4 commit f11349b) into the transfer inference path, reconciling with logic already synced into this repo, and adds CD smoke-test coverage for transfer inference.

• omni_mot_model.py already carries the velocity_postprocess_builder hook — no model change needed.
• transfer.py: add _build_no_control_inference_state and build_control_cfg_postprocess, wired through generate_samples_from_batch via velocity_postprocess_builder. Previously transfer.py passed control_guidance/control_guidance_interval directly, where they were silently dropped by **kwargs (control-CFG was a no-op).
• args.py: add emphasize_control_in_prompt (TransferDataArgs/Overrides + _TRANSFER_SAMPLE_DEFAULTS) to match the ported prompt-emphasis logic.

Test coverage

Extends tests/nano_inference_smoke_test.py (the generator-inference-smoke CD job) to also run a video2video edge transfer with control_guidance=1.5 in the same Nano inference call:

• Spec is built inline (_TRANSFER_SPEC, written to a temp file — not committed under inputs/), pulling the control video from the public NVIDIA/cosmos GitHub raw URL (same file the cookbook edge.json uses), downscaled for a fast smoke run (480p / 10 steps / single 29-frame chunk).
• Validates transfer-specific attributes (edge control_path, control_guidance > 1, guidance > 1) and a non-degenerate output clip via a new _assert_video_has_content helper (frame count + pixel variation).

Verification

Verified end-to-end on a GB200 node with this repo's .venv:

• README Nano edge transfer (control_guidance=1.5) → valid 121-frame 720p video; emphasize_control_in_prompt and the control-CFG path both run.
• Inline smoke spec → status: success, control_guidance=1.5, guidance=3.0, non-degenerate output (frames=29, pixel std ≈ 68).

Note: the branch name predates this work; after rebase it carries only the transfer commit (the curator-to-SFT converter already merged as #62).

🤖 Generated with Claude Code