release: prepare CsoKit 0.6.2

[HAKAMIQ]

Summary

• Prepare CsoKit 0.6.2.
• Update VERSION from 0.6.1 to 0.6.2.
• Update release notes with the three verified changes since v0.6.1.
• Record current release verification results.

Changes since 0.6.1

• Strengthen central managed/native version validation in release gates.
• Build, stage, and verify the native runtime used by release tests and published outputs.
• Remove the redundant native backend build from the GitHub release workflow.
• Clarify supported inspection formats and CSO2 verification wording.

Verification

• Verify-Hardening: PASS
• Official Release Gate: PASS
• NuGet Audit: PASS
• Debug build: PASS — 0 warnings, 0 errors
• Release build: PASS — 0 warnings, 0 errors
• Automated tests: 201/201 PASS
• Native integration: PASS
• Publish-Release: PASS
• Verify-Release: PASS
• Published executable smoke: PASS
• SHA256SUMS.txt: 6/6 entries verified
• Real ISO corpus gate: skipped for this validation run

Scope

Release preparation only. No unrelated changes.