2.2.0 release review notes

Review the release finalization as promotion of the merged 2.1 and 2.2 feature work. Confirm that the generated 2.2.0 API snapshot matches the current interfaces, stable metadata is consistent, historical evidence remains unchanged, and the clean-archive qualification passes on Linux and Windows.

The planned implementation slices and candidate qualification are complete. The remaining steps are to merge this release PR, verify CI on the resulting default-branch commit, and publish tag v2.2.0 from that commit.