Implements TGGNTrainableAdapter wrapping a candle-based projection network (input→hidden→ReLU→output) with full UnifiedTrainable interface including checkpoint save/load, validation, and gradient tracking. 11 tests covering forward, backward, optimizer step, checkpoint roundtrip, validation, learning rate, and metrics collection. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>