feat(cog-pose): per-room LoRA calibration adapter in the Rust inference path

Ports the calibration mechanism (ADR-150 §3.5-3.6, reference impl in
aether-arena/calibration/) into the real product pose engine. The Candle
InferenceEngine now loads an optional per-room adapter safetensors and
applies low-rank deltas (y + (x.A).B) on the fc1/fc2 head at inference.
Architecture-agnostic LoRA; base behaviour unchanged when no adapter.
New API: with_weights_and_adapter(), is_calibrated(). Tested: adapter
detection + output-change integration test (6/6 pass).

Co-Authored-By: claude-flow <ruv@ruv.net>