[Parity] Enable Pi0.5 in Round-Trip Validation

[DsThakurRawat]

Description

The ValidateRoundTrip orchestrator in src/reflex/validate_roundtrip.py explicitly excludes pi05 from its supported types, despite the model already being supported by the export and training pipelines.

Rationale

This prevents formal verification of the most advanced model in the Reflex suite. We should bring the validation layer into alignment with the rest of the stack.

Tasks

• Add pi05 to SUPPORTED_MODEL_TYPES.
• Verify that load_pytorch_backend and load_onnx_backend correctly handle the Pi0.5 architecture.
• Run a test validation on the official lerobot/pi05_base model.