chore: release v0.27.0

[mmcky]

Release prep for v0.27.0, per the AGENTS.md release checklist (steps 1–4): [Unreleased] promoted to [0.27.0] - 2026-09-01 with CHANGELOG entries added for the merges since v0.26.0 that had none (#293 prompt caching, #285 tool-review-injection/, #278 runReview extraction, #275 harness editors block) alongside the ml round-2 encoding (#297); version 0.26.0 → 0.27.0; dist-action rebuilt; full suite 1542 green, lint and format clean. .dev/STATE.md records the cut and moves W1 (#259) to v0.28.0.

Headline: the second Malayalam native-review round is encoded, and every translator call now uses prompt caching. Release notes are staged in .dev/scratch/release-notes.md.

After merge, per §4a: tag v0.27.0 on the merge commit → E2E-gate the tag (--action-ref v0.27.0) → move v0.27 and v0 → @v0 smoke (scenario 01) → GitHub release titled v0.27.0.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Release preparation for v0.27.0: bumps the package version, promotes the changelog to a dated release section describing the merged features/fixes, and updates the project state notes to record the release cut.

Changes:

• Bump npm package version to 0.27.0 (package.json, package-lock.json).
• Promote changelog entries into [0.27.0] - 2026-09-01 (CHANGELOG.md).
• Record the v0.27.0 release cut and adjust W1 targeting in .dev/STATE.md.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 3 comments.

File	Description
package.json	Bumps package version to 0.27.0.
package-lock.json	Keeps lockfile package version in sync at 0.27.0.
CHANGELOG.md	Adds the v0.27.0 release notes (but currently drops [Unreleased]).
.dev/STATE.md	Records the v0.27.0 release cut and updates roadmap notes (minor reference/date inconsistencies).

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[mmcky]

§4a gate record for v0.27.0 (tag on 125801c, 2026-09-01). Gate run --action-ref v0.27.0: 27 scenario PRs (test-translation-sync#775–#801), 9/9 workflows pinned to the tag, 81/81 sync runs succeeded; every lane delivered 27/27 with 27/27 verdicts stamped engineVersion: 0.27.0 / engineRef: v0.27.0 (routing ≈ half auto-merge / half editor, the known finding-rich regime). Floating tags moved: v0.27 and v0 → 125801c. Smoke --action-ref v0 --scenarios 01 (#802): all 9 workflows ran v0 at 125801c; zh-cn #818, fa #202 and ml #101 each carry engineVersion: 0.27.0 / engineRef: v0. Release created: https://github.com/QuantEcon/action-translation/releases/tag/v0.27.0 (Latest).