fix(builder): persist custom listing card fields

[syedgalib]

PR Type

What kind of change does this PR introduce?

• Bugfix
• Security fix
• Improvement
• New Feature
• Refactoring (no functional changes, no api changes)
• Build related changes
• Text changes
• Other... Please describe:

Description

Preserve stable custom-field widget keys while building listing resource card widget options. Saved card widgets are resolved through generated keys, original widget keys, and widget names so selected custom fields survive remount and save cycles.

How to reproduce the issue or how to test the changes

1. Add dynamic custom fields to the grid and list card layouts, both with and without thumbnails.
2. Save the directory builder, then reload or remount it.
3. Confirm the custom fields remain selected and both custom and built-in widgets continue to save correctly.

Any linked issues

N/A

Checklist

• My code follows the WordPress coding standards

[RabbiIslamRony]

@syedgalib, please remove the build and POT files. Also, resolve any merge conflicts.

[RabbiIslamRony]

@syedgalib I couldn't reproduce this locally.

[RabbiIslamRony]

@syedgalib The issue is reproducible locally, and the fix works correctly. However, a new issue appears with previously saved fields: they disappear after the first reload/save. If those fields are added again and saved, they persist correctly after reload. So, a migration is needed to normalize the previously saved field data.