Add train_launcher.sh that detects local GPU VRAM and routes training to local or Scaleway cloud. Auto-selects batch size per model based on available VRAM tier. Maps model names to actual ml/examples/train_*.rs cargo targets. Document Scaleway GPU instance types, setup procedure, batch size tables, and cost estimates. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>