CmdPal: Add URI protocol command to reload extension (#41445)

<!-- Enter a brief description/summary of your PR here. What does it
fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request

This PR introduces a new way to reload extensions externally and makes
the feature configurable in the settings UI.

- Adds a new URI protocol command `x-cmdpal://reload` → triggers an
extension reload
- Introduces a new "For Developers" section on the General settings page
- Includes an option to enable/disable the external reload feature
- **Note:** This change depends on the fix in #41344 to work correctly. 

Pictures? Pictures!

<img width="2312" height="1334" alt="image"
src="https://github.com/user-attachments/assets/6457ef5b-e75e-4118-86b7-7e20505527a3"
/>

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## PR Checklist

- [x] Closes: #40542 
- [ ] **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](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

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wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/SettingsModel.cs

@@ -42,6 +42,8 @@ public partial class SettingsModel : ObservableObject
 
     public bool IgnoreShortcutWhenFullscreen { get; set; }
 
+    public bool AllowExternalReload { get; set; }
+
     public Dictionary<string, ProviderSettings> ProviderSettings { get; set; } = [];
 
     public Dictionary<string, CommandAlias> Aliases { get; set; } = [];

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/SettingsViewModel.cs

@@ -38,6 +38,16 @@ public partial class SettingsViewModel : INotifyPropertyChanged
         }
     }
 
+    public bool AllowExternalReload
+    {
+        get => _settings.AllowExternalReload;
+        set
+        {
+            _settings.AllowExternalReload = value;
+            Save();
+        }
+    }
+
     public bool ShowAppDetails
     {
         get => _settings.ShowAppDetails;

src/modules/cmdpal/Microsoft.CmdPal.UI/MainWindow.xaml.cs

@@ -521,6 +521,21 @@ public sealed partial class MainWindow : WindowEx,
                             WeakReferenceMessenger.Default.Send<OpenSettingsMessage>(new());
                             return;
                         }
+                        else if (uri.StartsWith("x-cmdpal://reload", StringComparison.OrdinalIgnoreCase))
+                        {
+                            var settings = App.Current.Services.GetService<SettingsModel>();
+                            if (settings?.AllowExternalReload == true)
+                            {
+                                Logger.LogInfo("External Reload triggered");
+                                WeakReferenceMessenger.Default.Send<ReloadCommandsMessage>(new());
+                            }
+                            else
+                            {
+                                Logger.LogInfo("External Reload is disabled");
+                            }
+
+                            return;
+                        }
                     }
                 }
             }

src/modules/cmdpal/Microsoft.CmdPal.UI/Settings/GeneralPage.xaml

@@ -34,6 +34,8 @@
                   <RepositionThemeTransition IsStaggeringEnabled="False" />
               </StackPanel.ChildrenTransitions>-->
 
+                    <!--  'Activation' section  -->
+
                     <TextBlock x:Uid="ActivationSettingsHeader" Style="{StaticResource SettingsSectionHeaderTextBlockStyle}" />
 
                     <controls:SettingsExpander
@@ -66,6 +68,8 @@
                         </ComboBox>
                     </controls:SettingsCard>
 
+                    <!--  'Behavior' section  -->
+
                     <TextBlock x:Uid="BehaviorSettingsHeader" Style="{StaticResource SettingsSectionHeaderTextBlockStyle}" />
 
                     <controls:SettingsCard x:Uid="Settings_GeneralPage_ShowAppDetails_SettingsCard" HeaderIcon="{ui:FontIcon Glyph=&#xE8A0;}">
@@ -84,7 +88,16 @@
                         <ToggleSwitch IsOn="{x:Bind viewModel.ShowSystemTrayIcon, Mode=TwoWay}" />
                     </controls:SettingsCard>
 
-                    <!--  Example 'About' section  -->
+                    <!--  'For Developers' section  -->
+
+                    <TextBlock x:Uid="ForDevelopersSettingsHeader" Style="{StaticResource SettingsSectionHeaderTextBlockStyle}" />
+
+                    <controls:SettingsCard x:Uid="Settings_GeneralPage_AllowExternalReload_SettingsCard" HeaderIcon="{ui:FontIcon Glyph=&#xE777;}">
+                        <ToggleSwitch IsOn="{x:Bind viewModel.AllowExternalReload, Mode=TwoWay}" />
+                    </controls:SettingsCard>
+
+                    <!--  'About' section  -->
+
                     <TextBlock x:Uid="AboutSettingsHeader" Style="{StaticResource SettingsSectionHeaderTextBlockStyle}" />
 
                     <controls:SettingsExpander x:Uid="Settings_GeneralPage_About_SettingsExpander" HeaderIcon="{ui:BitmapIcon Source=ms-appx:///Assets/StoreLogo.png}">

src/modules/cmdpal/Microsoft.CmdPal.UI/Strings/en-us/Resources.resw

@@ -441,4 +441,13 @@ Right-click to remove the key combination, thereby deactivating the shortcut.</v
   <data name="NavigationPaneOpened" xml:space="preserve">
     <value>Navigation page opened</value>
   </data>
+  <data name="Settings_GeneralPage_AllowExternalReload_SettingsCard.Header" xml:space="preserve">
+    <value>Enable external reload</value>
+  </data>
+  <data name="Settings_GeneralPage_AllowExternalReload_SettingsCard.Description" xml:space="preserve">
+    <value>Trigger reload of the extension externally with the x-cmdpal://reload command</value>
+  </data>
+  <data name="ForDevelopersSettingsHeader.Text" xml:space="preserve">
+    <value>For Developers</value>
+  </data>
 </root>