chore: ignore out/ directory (training run artifacts)

Local training runs write to ./out/ by default (e.g. .checkpoint.json
from soup train). Add it to the existing training-outputs gitignore
block alongside output/ and checkpoints/.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -24,6 +24,7 @@ Thumbs.db
 
 # Training outputs
 output/
+out/
 checkpoints/
 wandb/