Prepare release 2.2.0

[cdcavell]

Summary

• Bumps shared build and template package version metadata from 2.1.0 to 2.2.0.
• Adds the 2.2.0 changelog entry covering the EF Core save-pipeline extraction, composite SaveChanges interceptor, ChangeTracker enumeration reduction, save-pipeline documentation, branch-focused interceptor tests, and package/documentation image refresh.
• Updates template package release notes for the 2.2.0 minor release.
• Updates README, package README, template packaging docs, citation metadata, and Zenodo metadata to reference 2.2.0.

Release Notes

This is a minor release because it introduces and documents a clearer EF Core save-pipeline extension seam while preserving the stable 2.x package identity, template short name, template options, and default scaffold behavior.

The default generated scaffold continues to use the same package identity, template identity, authentication options, data-access options, and local SQLite development path.

Validation

• Not run locally; changes were made through the GitHub connector.
• CI should run the release branch validation, including build, tests, coverage gate, template packing, scaffold smoke tests, and documentation checks.
• Before publishing, run the release gate items from RELEASE.md, including ./scripts/Validate-VersionConsistency.ps1.

Notes

• Branch was prepared from latest main, including the merged branch coverage test PR Add SaveChanges interceptor branch coverage tests #328.