Add validation to prevent empty names in ImageResizer size presets

[Copilot]

Summary of the Pull Request

Prevents users from clearing the name field in ImageResizer size preset edit dialog. Empty names made the UI confusing without causing errors.

PR Checklist

• Communication: I've discussed this with core contributors already. If the work hasn't been agreed, this work might be rejected
• Tests: Added/updated and all pass
• Localization: All end-user-facing strings can be localized
• Dev docs: Added/updated
• New binaries: Added on the required places
  • JSON for signing for new binaries
  • WXS for installer for new binaries and localization folder
  • YML for CI pipeline for new test projects
  • YML for signed pipeline
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Added validation guard in ImageSize.Name property setter:

public string Name
{
    get => _name;
    set
    {
        if (!string.IsNullOrWhiteSpace(value))
        {
            SetProperty(ref _name, value);
        }
    }
}

Invalid assignments (empty, null, whitespace) are silently ignored, preserving the existing value. This matches the existing pattern used for FileName validation in ImageResizerViewModel.

TwoWay binding in UI causes the TextBox to revert when users attempt to clear the field—standard behavior for required fields.

Validation Steps Performed

• Added unit test ImageSizeNameShouldNotBeSetToEmptyOrNull() covering all rejection and acceptance cases
• Verified silent rejection behavior matches FileName property pattern

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• i1qvsblobprodcus353.vsblob.vsassets.io
  • Triggering command: /usr/bin/dotnet dotnet build /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/Helpers/ResultHelper.cs /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/Helpers/RegistryHelper.cs /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/Enumerations/TruncateSide.cs /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/Constants/KeyName.cs /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/Constants/MaxTextLength.cs /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/Commands/CopyRegistryInfoCommand.cs /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/Commands/OpenKeyInEditorCommand.cs /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Re�� /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/CopyType.cs /home/REDACTED/work/PowerToys/PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Registry/Icons.cs (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Settings: ImageResizer] Edit size dialog: Add validation against empty name</issue_title>
<issue_description>There is one small thing we should add. (But I don't know how.)
The data in the name field of the edit dialog should be validated against .NullOrEmpty!
Originally posted by @htcfreek in #13285 (comment)

Detailed description:
While users edit an image size in the ImageResizer settings on PT's settings ux they are able to clear the name of the image size. This doesn't lead to errors/exceptions, but it also doesn't make sense to have sizes without a name. So we should prevent user from doing this in the edit dialog.

Note:
This is the second and last change that is needed to prevent the users from having incorrect image size settings (#8698). But I think this is not as relevant, because a missing name won't break image resizing._

---

cc: @niels9001 </issue_description>

<agent_instructions>Implement a proper fix for this issue. Do NOT create placeholder stub files. Create actual working code that addresses the issue described. Follow PowerToys coding guidelines and conventions.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@TheJoeFin does this issue still happen with v0.73.0? /needinfo

• Fixes [Settings: ImageResizer] Edit size dialog: Add validation against empty name #13336

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[htcfreek]

@copilot
Can we use text box input validation of winui text box control instead? Does such a feature exist? Because a user feedback would be good to have.