Larger text box for Idea Portal email domains

There is currently a single-line text box for entering approved email domains for our private idea portal. While allowing domain-based access is a huge improvement over sending individual invites, especially as users churn or change, managing this list in a single-line field becomes unworkable once we reach hundreds of domains. It’s difficult to view, edit, or validate what’s been entered, and it’s unclear whether the underlying database or UI control is meant to handle this volume in its current design.

We need to maintain hundreds, potentially thousands, of approved domains for user registration. With the current field setup, it’s nearly impossible to see what’s already included or to remove a single domain without copying the entire string out, reviewing it elsewhere, making edits, and pasting it back in. This creates risk for errors, slows down updates, and makes routine maintenance far more cumbersome than necessary.

As a first step, replace the single-line text box with a larger, resizable text area to improve visibility and basic editing; ensure that this is stored as a blob or provide additional fields to capture larger numbers of domains - need to consider portals that have thousands of users.

As a second iteration, evolve this into a proper list management experience where domains can be added, removed, sorted, and scanned individually, making the process far more reliable and scalable.