remove: delete obsolete cache.appcache file

[Ubayed-Bin-Sufian]

Fixes: #4665

Summary

This PR removes the deprecated cache.appcache file from the project. AppCache is an obsolete feature that is no longer supported in modern browsers due to security and performance concerns.

The removal aligns with best practices outlined in the following resources:

1. Chrome Developer Lighthouse: AppCache Manifest

2. Meteor Documentation: AppCache Package

3. Chromium Blink Dev Discussion on AppCache Deprecation

We have already migrated to a Service Worker-based approach for offline functionality, as implemented in sw.js, making the AppCache file redundant.

Checklist

• Removed cache.appcache from the codebase
• Verified there are no remaining references to AppCache

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[Ubayed-Bin-Sufian]

@walterbender, could you kindly advise which documentation file would be most appropriate for adding a note about the removal of the deprecated file?

[walterbender]

Maybe the Readme in the lib dir?

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[Ubayed-Bin-Sufian]

@walterbender Please review.

[walterbender]

I thought you were going to add info about how/when to deprecate packages to the Readme. We don't need to add this specific explanation. It should be in the commit message.

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[Ubayed-Bin-Sufian]

@walterbender I misunderstood. I suggest a change. Please review.

[github-actions]

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