Feat: add gemma3n support (#2852)

* feat: add gemma3n cce

* feat: add sample config

* feat: add gemma3n multimodal mode

* feat: add audio example

* feat: support audio and return pixel values in collator

* feat: support unmask only assistant region (gemma3n for now)

* feat(doc): add notes for audio loading

* feat: add audio support for gemma3n

* feat: update examples

* feat: add gemma3n to the docs

* fix: add link at top

* feat(doc): clarify additional requirements

* fix: mllama missing aspect ratio

* fix: mllama need attention fixes for fa2

* Partially Revert "fix: mllama need attention fixes for fa2"

This reverts commit a0bfdd1777.

* fix: disable FA2 for mllama in vision mode

* feat: update configs to use proper attention

* fix: support other vision features

* feat(doc): clarify requirements for gemma3n

examples/mistral/mistral-small-3.1-24B-lora.yml

@@ -48,8 +48,8 @@ tf32: true
 
 gradient_checkpointing: true
 logging_steps: 1
-flash_attention: false # PixtralVisionModel does not support Flash Attention 2.0 yet.
-eager_attention:
+# flash_attention: false # PixtralVisionModel does not support Flash Attention 2.0 yet.
+sdp_attention: true
 
 warmup_ratio: 0.1
 evals_per_epoch: 1