Extend checkpoint_roundtrip.rs with 4 new tests for sequence-buffered models:
- TFT adapter deterministic inference: verifies same adapter produces
identical direction/confidence on repeated calls with stable buffer
- TFT quantile metadata: confirms quantiles are absent during buffering
phase and present (with correct count) after buffer fills
- Mamba2 adapter deterministic inference: same pattern as TFT, verifies
direction/confidence stability and correct model name ("MAMBA-2")
- Mamba2 CheckpointManager roundtrip: saves/loads via Checkpointable
trait on Mamba2SSM, verifies metadata tags and hyperparameters
All 10 tests (6 existing DQN/PPO + 4 new TFT/Mamba2) pass consistently.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>