Upgrade Node version to 24 (APS-19023)

[Raghav11-11]

Summary

Migrates all actions in this repo from node20 (and node16 for browserstack-report-action) to node24 to address GitHub's Sept 2025 Node 20 deprecation. Customers using @master are seeing a deprecation warning in their workflow runs today; once Node 20 is removed in Fall 2026 the actions will fail to start.

Tracking ticket: APS-19023

Changes

• action.yml — node20 → node24
• setup-env/action.yml — node20 → node24
• setup-local/action.yml — node20 → node24
• browserstack-report-action/action.yml — node16 → node24
• .github/workflows/setup-env.yml — node-version: 20.x → 24.x
• .github/workflows/setup-local.yml — node-version: 20.x → 24.x

No source or dist/ changes — only the runtime declaration.

Test plan

• Local: npm install && npm test on Node 24 in all three sub-actions (117 tests passing — 36 setup-env, 63 setup-local, 18 browserstack-report-action)
• Repo CI: this repo's setup-env / setup-local workflows pass on ubuntu-latest / macos-latest / windows-latest once the PR opens
• End-to-end smoke: consume setup-env + setup-local from this branch in a downstream test repo, confirm the deprecation warning is gone and tunnel start/stop work

Notes for reviewers

• Customer impact at merge time: every consumer pinned to @master picks this up on their next CI run (no semver tags maintained on this repo).
• node24 requires self-hosted runner version ≥ 2.327 (released Sept 2025). Customers on stale self-hosted runners may need to upgrade; can document in README as a follow-up if support sees tickets.
• browserstack-report-action's dist/index.js is stale on master (pre-commit hook hasn't been run for a while). That's a separate cleanup, not in scope here.