Support Custom Fields as Columns in Game List View

📋 Summary

Allow user created custom fields to be added as selectable columns within the LaunchBox game list view, alongside existing built in metadata columns.

❗ Problem

LaunchBox currently supports custom fields for storing additional metadata, but these fields cannot be surfaced directly as columns in the main game list view.

This limits their usefulness for users who rely on custom metadata for organization, filtering, workflows, or collection management.

At the moment:

• Custom fields can only be viewed inside Edit Metadata windows

• Users cannot quickly scan or sort by custom field values in the game list

• Workflows relying on custom metadata become cumbersome for large collections

💡 Proposal

Extend the game list column system to support custom fields.

Features could include:

• Add custom fields to the existing column selector menu

• Support sorting by custom field values

• Preserve custom column layouts across views and theme