* Add support for sage attention 3 in comfyui, enable via new cli arg
--use-sage-attiention3
* Fix some bugs found in PR review. The N dimension at which Sage
Attention 3 takes effect is reduced to 1024 (although the improvement is
not significant at this scale).
* Remove the Sage Attention3 switch, but retain the attention function
registration.
* Fix a ruff check issue in attention.py