CmdPal: Improve Command Palette behavior in "Last position" mode (#43543)

## Summary of the Pull Request

This PR improves Command Palette behavior in “Last position” mode:
- Correctly handles DPI changes between monitors.
- Ensures the window is always visible — if it’s fully off-screen or has
less than 100px visible on any axis, it is re-centered.



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## PR Checklist

- [x] Closes: #43398
- [ ] **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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## Detailed Description of the Pull Request / Additional comments

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## Validation Steps Performed

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

@@ -2,21 +2,52 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using Windows.Graphics;
 
 namespace Microsoft.CmdPal.UI.ViewModels;
 
 public sealed class WindowPosition
 {
+    /// <summary>
+    /// Gets or sets left position in device pixels.
+    /// </summary>
     public int X { get; set; }
 
+    /// <summary>
+    /// Gets or sets top position in device pixels.
+    /// </summary>
     public int Y { get; set; }
 
+    /// <summary>
+    /// Gets or sets width in device pixels.
+    /// </summary>
     public int Width { get; set; }
 
+    /// <summary>
+    /// Gets or sets height in device pixels.
+    /// </summary>
     public int Height { get; set; }
+
+    /// <summary>
+    /// Gets or sets width of the screen in device pixels where the window is located.
+    /// </summary>
+    public int ScreenWidth { get; set; }
+
+    /// <summary>
+    /// Gets or sets height of the screen in device pixels where the window is located.
+    /// </summary>
+    public int ScreenHeight { get; set; }
+
+    /// <summary>
+    /// Gets or sets DPI (dots per inch) of the display where the window is located.
+    /// </summary>
+    public int Dpi { get; set; }
+
+    /// <summary>
+    /// Converts the window position properties to a <see cref="RectInt32"/> structure representing the physical window rectangle.
+    /// </summary>
+    public RectInt32 ToPhysicalWindowRectangle()
+    {
+        return new RectInt32(X, Y, Width, Height);
+    }
 }