ci: make yarn install --immutable explicit in CI workflows

[dev-hari-prasad]

Part of #10363.

Yarn's enableImmutableInstalls setting already defaults to true when CI is present in the environment (such as in GitHub Actions).

Passing --immutable explicitly to yarn install in our CI workflows makes the intended immutable lockfile enforcement self-documenting and transparent to future contributors and maintainers.

Changes

• Added --immutable to yarn install across the 4 GitHub Actions workflows:
  • check-javascript-style.yml
  • run-javascript-tests.yml
  • run-feature-tests-epas.yml
  • run-feature-tests-pg.yml

Summary by CodeRabbit

• Chores
  • Updated automated workflows to use lockfile-consistent dependency installation.
  • Builds, style checks, and JavaScript tests now fail when dependency definitions and the lockfile are out of sync.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Team

Run ID: 57576163-e2a9-497d-ae06-e6153304c63d

📥 Commits

Reviewing files that changed from the base of the PR and between bd7cde5 and 8899d2e.

📒 Files selected for processing (4)

• .github/workflows/check-javascript-style.yml
• .github/workflows/run-feature-tests-epas.yml
• .github/workflows/run-feature-tests-pg.yml
• .github/workflows/run-javascript-tests.yml

Included review availability: Your plan provides up to 8 included reviews per hour; 7 remain after this review.

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Walkthrough

The JavaScript style, EPAS feature-test, PostgreSQL feature-test, and JavaScript test workflows now use yarn install --immutable. Installs fail when the lockfile and package manifest are inconsistent.

Changes

CI install consistency

Layer / File(s)	Summary
Enforce immutable Yarn installs .github/workflows/check-javascript-style.yml, .github/workflows/run-feature-tests-epas.yml, .github/workflows/run-feature-tests-pg.yml, .github/workflows/run-javascript-tests.yml	The workflow install steps now use yarn install --immutable and fail when installation would modify the lockfile.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 8899d

The workflows now fail rather than silently updating an inconsistent Yarn lockfile, improving CI dependency reproducibility. No current merge-readiness risk is identified.

Suggested reviewers: dpage

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: making yarn install --immutable explicit in four CI workflows.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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