[WIP] Migrate CI scripts from bash to JavaScript with measurable improvements

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

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This section details on the original issue you should resolve

<issue_title>[Build/CI] Migrate CI scripts from bash to JavaScript with specific, testable improvements</issue_title>
<issue_description>## Build/CI Summary

Expand and clarify the migration to JavaScript-based CI/automation scripts by listing the mandatory, measurable improvements and explicit outputs the team must deliver.

Specific CI Improvements

• Replace brittle bash scripts (CI entrypoints, version sync, environment setup and teardown) with maintainable JavaScript tools.
• Isolate all test and build scripts so they may execute in CI, local dev, or ephemeral environments (no hardcoded paths / platform assumptions).
• Add robust error handling, clear exit codes, and detailed logging to all scripts for faster diagnosis and more actionable feedback in CI runs.
• Ensure scripts automatically sanitise/validate all external input and escape outputs (for env, shell, and config writes).
• Standardise Node.js script entrypoints to support cross-platform use (npx, node, or package.json scripts) and support repo-standard CLI arguments.
• Script output (esp. build artefacts or logs) must pipe cleanly to CI consumers and commit hooks without formatting/unexpected file writes.
• Remove dependency on system-installed Unix tools (e.g. sed/awk/grep). If tiny POSIX utility is required, use a vetted Node.js equivalent instead (document justification in code).
• Where applicable, add dry-run and verbose flags for safe scripting/experimentation in CI or PR checks.
• Add or update unit/integration tests so scripted steps run in parallel on supported CI runners (Windows/macOS/Linux), with output artefacts and side effects verified in repo-specific test jobs.
• Update CI docs, CONTRIBUTING, and developer onboarding docs to point only at JS-based scripts, including usage examples and common troubleshooting.

Expected Deliverables

• All required bash scripts replaced and removed from repo.
• JavaScript scripts present in /scripts (or similar), following repo structure.
• All affected CI workflow YAMLs (GitHub Actions, etc) refactored to use new scripts.
• All scripts pass linting/format checks; tested on all supported CI runners.
• Documentation updated and verified.
• Sample logs and artefact outputs attached to PR or referenced in docs.
• Change summary and rationale documented for reviewer sign-off.

Steps / Checklist

• Replace all CI bash scripts with JavaScript tools (see above)
• Enforce script validation (input sanitisation, contextual escaping)
• Write/expand CI tests to validate outputs, logging, and cross-platform support
• Refactor all affected workflows and docs to remove obsolete shell script references
• Documentation updated (usage, troubleshooting, compatibility)
• PR uses correct branch prefix (ci/ or build/)

Acceptance Criteria

• All listed CI outputs delivered: scripts, docs, test coverage, logs
• Bash scripts and workflow shims removed from all automated paths
• All scripts linted, pass tests, and CI green on all platforms
• Approach approved by maintainers
  </issue_description>

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