test: 20 *.test.cjs files never run (testMatch omits .cjs); 18 fail when run #3484

Problem

.jest.config.cjs testMatch covers *.test.js, *.test.ts and *.test.mjs, but not *.test.cjs. The 20 tracked *.test.cjs files outside archived/ never run, so their failures are invisible.

Forced run (JEST_TEST_MATCH_*="**/*.test.cjs", 2026-09-23): 18 of 20 suites fail, 21 of 118 tests.

Failing suites:

• agents/changelog-agent/includes/tests/{keepAChangelogParser,changelogValidator}.test.cjs
• agents/release-agent/__tests__/{integration,gitOps}.test.cjs, agents/release-agent/includes/tests/{versionManager,repoDetector}.test.cjs
• agents/wordpress-release-utilities-agent/includes/tests/readmeTxt.test.cjs
• scripts/automation/__tests__/update-projects-status.test.cjs
• scripts/validation/__tests__/validate-labels-before-creation.test.cjs
• scripts/workflows/__tests__/orchestrate-phase-progression.test.cjs (this one only tests helpers defined inside the test file itself)
• scripts/workflows/changelog/__tests__/{checkout-pr-head,merge-entries.integration,merge-entries,changelog-management}.test.cjs
• scripts/workflows/metrics/__tests__/metrics-reporting.test.cjs
• scripts/workflows/projects/__tests__/{scan-completion,archive-projects}.test.cjs
• scripts/workflows/release/__tests__/trigger-telemetry.test.cjs

Change

• Triage each suite: fix the test or the code, or delete tests that test nothing real.
• Add **/*.test.cjs to testMatch (both tests/ and __tests__/ forms, see task: support tests/ and __tests__/ and remove dead root jest.config.js #3469) once they pass, so they gate CI through fix(ci): no workflow runs the Jest suite, so test regressions merge green #3479.

Acceptance

• npx jest --config .jest.config.cjs --listTests includes every tracked *.test.cjs, and all of them pass.

Relates to #3469, #3472, #3479