chore: release v1.6.0

[skyoo2003]

Pull Request

Description

Cuts v1.6.0. Generated by changie batch v1.6.0 + changie merge — no hand edits.

Version justification. Two independent signals agree on a minor bump:

Signal	Evidence
Fragment kinds	2 × Added (#243, #244), 1 × Documentation (#245)
Public API delta	git diff v1.5.2..main -- api/v1.txt → +120, −0
gorelease -base=v1.5.2	Suggested version: v1.6.0, every entry added

No entry of the frozen v1 surface was removed or changed, so nothing here is a compatibility break.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Test update

Release chore — none of the above. No source file changes; only CHANGELOG.md and changes/.

Checklist

• Tests pass (make test) — no Go files changed; pre-commit skipped the Go hooks for that reason
• Vet/make vet — same
• Linting passes (make lint) — same
• Build succeeds (make build) — same
• Documentation updated if needed — N/A, release chore
• Changelog fragment added (changie new) — N/A, this PR consumes the fragments
• Commit messages follow guidelines

Additional Notes

go.mod's retract [v1.0.0, v1.4.0] block is untouched, so the Verify retraction block CI step should pass and the retractions ship with this release.

After merge, per RELEASE.md: sync main, then tag the merge commit (not this branch) and push v1.6.0 to trigger the release build.

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By submitting this PR, I agree that my contributions will be licensed under the Apache License 2.0.