Support for node 18 & removed dependency of Preview Host.

[Contentstack-AnkitaD]

📌 Summary

This PR updates the contentstack-angular-starter master branch to make it production-ready for Marketplace deployment with Live Preview support.

✅ Key Changes

• Live Preview Optimization:

  • preview_host is now dynamically derived from CONTENTSTACK_APP_HOST if not explicitly set.

  • Updated .env.sample with necessary Live Preview environment variables:

    • CONTENTSTACK_PREVIEW_TOKEN
    • CONTENTSTACK_APP_HOST
    • CONTENTSTACK_LIVE_PREVIEW

• Node Version Update:

  • Updated package.json to require Node >=18.0.0 to match deployment compatibility.

• Environment Config Enhancements:

  • Added logic in setenv.ts to generate preview_host from app_host.
  • Ensured fallback values for branch and region if not provided.

🔒 Talisman Update

• Added .env.sample and setenv.ts to .talismanrc with respective SHA checksums to avoid false positives during secret scans.

🗂️ Files Modified

• .env.sample
• package.json
• setenv.ts
• .talismanrc
• package-lock.json

🎯 Purpose

To ensure the Angular starter master branch works seamlessly with Marketplace deployment and supports secure Live Preview integration without relying on the management token.

[Contentstack-AnkitaD]

We NO MORE need this work-around logic, hence closing the PR.
CREATING A SEPARATE PR FROM MAIN BRANCH FOR NODE 18 UPDATE