W29 - Model lifecycle & promotion pipeline

How a model change ships: offline eval against the rubric → shadow mode beside the live adapter (output never shown to users) → canary A/B through the experiments console (W30) → promotion behind a required human sign-off → post-promote monitoring with a warm rollback target. No stage can be skipped, including for hosted-API swaps through the adapter interface; accepted/edited/rejected outputs from W23/W25/W26 become the next version's training set.