fix: make normalize(x1) assignment explicit in training loop

normalize() uses in-place ops so it worked, but reading the return value
makes the intent clear and guards against future refactors.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nodes/selva_lora_trainer.py

@@ -740,7 +740,7 @@ class SelvaLoraTrainer:
                 sync_f    = torch.stack([x.squeeze(0) for x in sync_list]).to(device, dtype)
                 text_clip = torch.stack([x.squeeze(0) for x in text_list]).to(device, dtype)
 
-                generator.normalize(x1)
+                x1 = generator.normalize(x1)
 
                 if timestep_mode == "logit_normal" or (
                     timestep_mode == "curriculum" and step <= curriculum_switch_step