Bump AITER to 4fa508ef

[lauri9]

Bump AITER to 4fa508ef and refresh CI patches for PyTorch 2.9 compatibility.

Closes #979

Background

Part of plan to remove triton attention.

Upstream AITER is bumped forward to 4fa508ef, which brings in the MHAv4 API and changes file layout and type annotations.

On the current PyTorch 2.9 stack, AITER's nested _validate_cu helper in aiter/ops/mha.py uses PEP 604 (X | None) syntax that causes a Dynamo graph break under torch.compile. This is resolved in the PR with a temporary patch.

Goals

• Update AITER to add support for mha_v4 API
• Keep the FP8 sparse ASM kernel patch applying cleanly against the bumped AITER revision.
• Restore torch.compile compatibility for AITER MHA on PyTorch 2.9 with temporary patch

Tasks

• Bump AITER_COMMIT to 4fa508ef2935110ff99adf2743ea93807dbd9c67 in docker/Dockerfile.ci.
• Regenerate patches/aiter_fp8_sparse_asm_kernel.patch for the new AITER layout (retargeted hunks, updated mutates_args typing).
• Add patches/aiter_mha_pep604_dynamo.patch and apply it in the CI Dockerfile to replace PEP 604 annotations with Optional[...] in _validate_cu.

Tests

• CI core image build succeeds with bumped AITER and refreshed patches.
• Validate performance and visual quality on gfx942 & gfx950 - CI run
• Validate inference / torch.compile paths that exercise AITER MHA on PyTorch 2.9.

Performance on MI350X - no significant changes

model	AITER bump	Baseline	Ratio
flux.usp	0.84	0.85	101.0%
flux.single_gpu	2.38	2.41	101.3%
flux.usp_2k	2.22	2.25	101.1%
flux.single_gpu_2k	12.03	12.16	101.1%
flux2.default	4.48	4.52	100.8%
flux2.quantgemm.gfx950	2.45	2.47	100.7%
flux2.quantgemm_sageattn.gfx950	2.57	2.61	101.6%
flux2.ti2i_2k	12.57	12.53	99.7%
flux2.t2i_1k	2.90	2.91	100.3%
flux2.t2i_2k	10.75	10.72	99.8%
flux2.t-multi-i2i_1k	5.99	5.95	99.3%
flux2.t-multi-i2i_2k	15.04	15.02	99.9%
flux2_klein.default	0.49	0.49	100.2%
flux_kontext.default	1.50	1.50	100.2%
hunyuanvideo.default	104.91	104.06	99.2%
hunyuanvideo.fp8attn	66.04	66.39	100.5%
hunyuanvideo.sageattn.gfx950	87.62	88.00	100.4%
hunyuanvideo_1_5.default	116.42	116.71	100.2%
hunyuanvideo_1_5.distilled.gfx950	54.80	55.18	100.7%
hunyuanvideo_1_5.distilled_sparse.gfx950	45.52	46.04	101.2%
ltx2_3.default	16.14	16.17	100.2%
qwen_image.default	4.83	4.89	101.2%
qwen_image_edit.default	14.97	15.12	101.1%
stablediffusion_3_5.default	0.81	0.81	100.1%
wan2_1.default	73.83	74.54	101.0%
wan2_2.default	75.72	75.99	100.4%
wan2_2.quantgemm.gfx950	67.83	68.76	101.4%
wan2_2.quantgemm_fp8attn.gfx950	40.85	41.17	100.8%
wan2_2.quantgemm_sageattn.gfx950	53.30	54.72	102.7%
wan2_2.quantgemm_spargeattn.gfx950	30.79	31.03	100.8%
z_image.default	2.65	2.67	101.1%

Performance on MI300X - no significant changes

model	AITER bump	Baseline	Ratio
flux.usp	1.29	1.29	99.6%
flux.single_gpu	3.80	3.81	100.3%
flux.usp_2k	3.77	3.78	100.1%
flux.single_gpu_2k	20.02	20.03	100.1%
flux2.default	7.67	7.74	100.9%
flux2.quantgemm.gfx942	5.47	5.51	100.7%
flux2.quantgemm_sageattn.gfx942	5.74	5.78	100.7%
flux2.ti2i_2k	22.54	22.58	100.2%
flux2.t2i_1k	5.04	5.05	100.2%
flux2.t2i_2k	18.58	18.59	100.1%
flux2.t-multi-i2i_1k	9.99	10.00	100.1%
flux2.t-multi-i2i_2k	25.60	25.60	100.0%
flux2_klein.default	0.79	0.79	99.1%
flux_kontext.default	2.46	2.46	100.1%
hunyuanvideo.default	179.92	178.85	99.4%
hunyuanvideo.fp8attn	129.91	131.46	101.2%
hunyuanvideo.sageattn.gfx942	147.56	149.88	101.6%
hunyuanvideo_1_5.default	218.58	218.53	100.0%
hunyuanvideo_1_5.distilled.gfx942	105.35	107.52	102.1%
hunyuanvideo_1_5.distilled_sparse.gfx942	81.15	81.74	100.7%
ltx2_3.default	27.47	27.80	101.2%
qwen_image.default	8.18	8.16	99.8%
qwen_image_edit.default	22.60	22.57	99.9%
stablediffusion_3_5.default	1.25	1.26	100.3%
wan2_1.default	133.40	134.02	100.5%
wan2_2.default	133.30	133.80	100.4%
wan2_2.quantgemm.gfx942	121.27	121.78	100.4%
wan2_2.quantgemm_fp8attn.gfx942	88.18	88.46	100.3%
wan2_2.quantgemm_sageattn.gfx942	99.57	102.01	102.4%
wan2_2.quantgemm_spargeattn.gfx942	73.92	75.18	101.7%
z_image.default	4.52	4.53	100.2%

Other

• The Dynamo workaround patch is intentionally temporary and documented inline in docker/Dockerfile.ci.