release: v4.3.23

[326sun]

Overview

Prepare Runtime Self-Learning v4.3.23 as the formal v4.x LTS complexity governance release.

This PR now contains:

• Complexity governance infrastructure and budgets.
• Low-risk C-001 split of tools/control.js.
• Release readiness integration via complexity.within_budget.
• v4.3.23 version and release documentation updates.

Changes

Complexity governance

• Add lib/complexity.js as the in-repo complexity budget source.
• Add scripts/complexity-check.js and scripts/complexity-report.js.
• Add docs/COMPLEXITY_BUDGET.md, docs/COMPLEXITY_DEBT.md, and docs/COMPLEXITY_REPORT.md.
• Wire complexity.within_budget into release:check.

Control-surface cleanup

• Extract tools/control-parameters.js.
• Extract tools/control-summaries.js.
• Extract low-risk handlers under tools/control-handlers/.
• Keep high-risk / low-return handler migration deferred and documented.

Release preparation

• Bump package.json, manifest.json, and package-lock.json to 4.3.23.
• Add CHANGELOG.md entry for 4.3.23.
• Add docs/ACCEPTANCE-v4.3.23.md.
• Sync README / install / design-matrix release references.

Verification

Local verification completed:

• npm run check passed
• npm test passed: 665 pass, 0 fail, 0 skipped
• npm run complexity:check passed: 0 violations, 3 soft warnings
• npm run complexity:report passed
• npm run release:check passed: ready, score 100
• npm run benchmark passed: 17/17 scenarios succeeded
• npm run perf passed: all metrics within thresholds

Boundaries

• No runtime dependency added.
• Security policy not relaxed.
• No benchmark-results/ committed.
• No force push.
• No direct push to main.
• No merge in this step.
• No tag created or moved in this step.
• No release created or modified in this step.