docs: align current release documentation

[codeforester]

Summary

• make the published v2.2.0 documentation the single current-release source of truth;
• correct the README, quickstart, versioning policy, pinned-consumption, discovery, and first-party validation references to the verified v2.2.0 commit;
• keep the process module consistently described as preview-only while recording that it first shipped in v2.1.0;
• make the documentation contract derive its expected release version from VERSION, require one shared full commit across the quickstart and README, and compare it with the published tag when available.

Issue

Fixes #567

Validation

• git diff --check
• bash tests/docs-contract.sh
• ./tests/validate.sh — 712 tests plus release, artifact, property, integration, quality, and CI-policy stages passed.

Release safety

This is documentation and contract-test work only. It does not change VERSION, release artifacts, or the immutable v2.2.0 tag.