chore: update submodule refs + ignore training checkpoints

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

Author: Antigravity Agent

.gitignore

@@ -257,3 +257,4 @@ hslm-train
 hslm-train/
 --output
 --output/
+data/checkpoints_v3/