Fix stable Workflow release identity

[rmcdaniel]

Summary

• accept only exact stable 2.x.y product-train identities after the 2.0 launch
• prepare the corrective 2.0.2 package metadata and changelog
• exercise the public package identity accessor in the platform conformance test

Why

Published-package verification for 2.0.1 installed successfully, then failed because PlatformConformanceSuite::workflowSourceRelease() still required an RC-only version. The retained 2.0.0-rc.42 artifact provenance remains unchanged; this patch fixes only the current package identity.

Verification

• PlatformConformanceSuiteTest: 20 tests, 571 assertions
• focused package identity test: 1 test, 42 assertions
• ECS on changed PHP files
• public-boundary scan
• git diff --check