docs: update v0.2 governance changelog

[CoderDeltaLAN]

Summary

• Update the unreleased changelog with the current v0.2 governance work on main.
• Document governance rules, CLI output coverage, structured finding evidence, evidence redaction, and conservative safety wording.
• Preserve v0.1.0 as the only published release.

Scope

• CHANGELOG.md only.
• No code, tests, README, SECURITY, pyproject, CI, release, tag, or dependency changes.

Verification

• 93 tests passed locally through ./scripts/check.sh.
• Diff is limited to CHANGELOG.md.
• v0.1.0 tag/release verified intact before push.