Fix: Correct hidden state return value in forward method

### Problem

The `forward` method in `modeling.py` line 646 incorrectly assigns `outputs.hidden_states` to the `hidden_states` field in its return object.

The correct tensor, `outputs.last_hidden_state`, is already computed and used internally to calculate the logits, but it is effectively discarded in the final return value.

### Solution

This commit corrects a single variable in the `return` statement. It changes `outputs.hidden_states` to `outputs.last_hidden_state`, ensuring the final hidden state tensor is correctly passed through.

This makes the model's output useful for feature extraction and analysis, fixing the intended behavior without any other functional changes.

modeling.py

@@ -643,7 +643,7 @@ class Fast_dLLM_QwenForCausalLM(Fast_dLLM_QwenPreTrainedModel, GenerationMixin):
             loss=loss,
             logits=logits,
             past_key_values=outputs.past_key_values,
-            hidden_states=outputs.hidden_states,
+            hidden_states=outputs.last_hidden_state,
             attentions=outputs.attentions,
             block_past_key_values=outputs.block_past_key_values,
         )