No user-facing error when creating a new folder with a duplicate name in "Manage Library"

Overview

When attempting to add a new folder in the "Manage Library" section with a name that already exists under the same parent (e.g., Components, Patterns, or Code), there is no user-facing error message to indicate the name conflict. Instead, a 422 error is returned in the console and network tab, but the UI does not display any validation message to the user. This can lead to confusion, as it appears the folder creation failed silently.

Steps to Reproduce

1. In "Manage Library", click the Add New Folder button within a desired parent section (e.g., Components, Patterns, or Code).
2. Enter a folder name that already exists under that parent.
3. Click Add Folder.
4. Observe that no validation error is shown in the UI, but a 422 error appears in the browser console and network tab.

Expected Result:
A clear, user-friendly validation error should be shown in the UI, notifying the user that the folder name must be unique within the selected parent.

Proposed resolution

User interface changes