Card image: blur-fill behind a uniform-fit foreground

Portrait source images were getting cropped by UniformToFill (chins /
hands cut off), but switching to Uniform would letterbox wide images
in the otherwise-square card slot. Add a two-layer pattern: the same
image at UniformToFill with a BlurEffect fills the slot edge-to-edge
behind a Uniform foreground that always shows the full image. No
crop, no empty bars — the blurred edges feel like a natural extension
of the picture.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: mohnjiles

StabilityMatrix.Avalonia/Views/CivArchiveBrowserPage.axaml

@@ -134,11 +134,26 @@
                         </LayoutTransformControl.LayoutTransform>
                         <Grid Width="330" RowDefinitions="300,Auto">
                             <Grid ClipToBounds="True">
+                                <!--
+                                    Two-layer blur-fill so portrait images aren't cropped (Uniform on the
+                                    foreground keeps the whole image visible) but we don't get letterbox
+                                    bars either (the same image, blurred and UniformToFilled, fills the
+                                    leftover space behind it).
+                                -->
                                 <controls:BetterAdvancedImage
                                     CornerRadius="8"
                                     IsVisible="{Binding ImageUrl, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
                                     Source="{Binding ImageUrl}"
-                                    Stretch="UniformToFill" />
+                                    Stretch="UniformToFill">
+                                    <controls:BetterAdvancedImage.Effect>
+                                        <BlurEffect Radius="24" />
+                                    </controls:BetterAdvancedImage.Effect>
+                                </controls:BetterAdvancedImage>
+                                <controls:BetterAdvancedImage
+                                    CornerRadius="8"
+                                    IsVisible="{Binding ImageUrl, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
+                                    Source="{Binding ImageUrl}"
+                                    Stretch="Uniform" />
 
                                 <!--  Placeholder when no image  -->
                                 <Border Background="{DynamicResource ControlAltFillColorSecondaryBrush}" IsVisible="{Binding ImageUrl, Converter={x:Static StringConverters.IsNullOrEmpty}}">