5c9a884c3f
Ports the FP4 quantization config + ops from FastVideo-internal (fastvideo.layers.quantization.fp4_config). flashinfer is imported lazily inside _require_flashinfer() rather than at module top so ``import fastvideo`` stays cheap on hosts that don't ship flashinfer — the FP4 kernels themselves still raise a clear ImportError pointing at ``pip install flashinfer-python`` when invoked. Behavior is identical to the internal version: * FP4Config: LTX-2 layer set (48 transformer blocks across attn1/attn2 /audio_to_video_attn/video_to_audio_attn/ffn plus adaln_single.linear), layer_profile selects between "base" and "refine" stage subsets. * FP4QuantizeMethod: per-layer quantize_input + apply with stage-aware routing for refine-only layers (audio_to_video_attn.to_q, video_to_audio_attn.to_k, video_to_audio_attn.to_v fall through to dense F.linear during the base stage). * convert_model_to_fp4(): pre-quantize weight buffers + alpha onto module attrs at load time so the forward path doesn't pay the per-step weight-side quantize cost. Required for Dreamverse integration: dreamverse-server's GPU worker runs ``pipeline_config.dit_config.quant_config = FP4Config()`` during LTX-2 model load, which is the dominant inference path. test_fp4_config covers the lazy-flashinfer contract: import succeeds without flashinfer; layer_profile round-trips via from_config; calling into _require_flashinfer raises ImportError with an actionable message when flashinfer is missing. Co-authored-by: Junda (David) Su <90978028+Davids048@users.noreply.github.com> Co-authored-by: Matthew Noto <99706358+RandNMR73@users.noreply.github.com> Co-authored-by: XOR-op <17672363+XOR-op@users.noreply.github.com> Co-authored-by: Zhang Peiyuan <42993249+jzhang38@users.noreply.github.com>