feat(ui): wählbares Listen-Icon und aufgeräumter Task-Detail-Header

Listen bekommen eine Icon-Spalte (Migration AddListIcon) und einen Icon-Picker
in den Listeneinstellungen; 34 kuratierte Geometrien aus der Icon-Bibliothek,
Fallback auf "Folder" bei unbekanntem Key.

Der Metadata-Footer im Task-Detail entfällt; created-at wandert in die
Header-Zeile neben das ID-Badge, der Close-Button (und CloseDetailsCommand)
fällt weg.

src/ClaudeDo.Ui/Views/Islands/Detail/TaskHeaderBar.axaml

@@ -10,12 +10,15 @@
 
     <!-- Column 0: id badge + editable title -->
     <StackPanel Grid.Column="0" Spacing="0">
-      <TextBlock Classes="meta"
-                 Text="{Binding TaskIdBadge}"
-                 Margin="0,0,0,4"
-                 Cursor="Hand"
-                 ToolTip.Tip="{loc:Tr details.copyTaskIdTip}"
-                 Tapped="OnTaskIdTapped"/>
+      <StackPanel Orientation="Horizontal" Spacing="8" Margin="0,0,0,4">
+        <TextBlock Classes="meta"
+                   Text="{Binding TaskIdBadge}"
+                   Cursor="Hand"
+                   ToolTip.Tip="{loc:Tr details.copyTaskIdTip}"
+                   Tapped="OnTaskIdTapped"/>
+        <!-- created-at moved up from the removed metadata footer -->
+        <TextBlock Classes="meta" Text="{Binding Task.CreatedAtFormatted}"/>
+      </StackPanel>
       <TextBox Text="{Binding EditableTitle, Mode=TwoWay}"
                Background="Transparent"
                BorderThickness="0"

src/ClaudeDo.Ui/Views/Islands/DetailsIslandView.axaml

@@ -11,27 +11,6 @@
   <Panel>
   <DockPanel>
 
-    <!-- ── Metadata footer (sticky bottom) — created-at + close — task detail only ── -->
-    <Border DockPanel.Dock="Bottom"
-            IsVisible="{Binding IsTaskDetailVisible}"
-            BorderBrush="{DynamicResource LineBrush}"
-            BorderThickness="0,1,0,0"
-            Padding="14,8">
-      <Grid ColumnDefinitions="*,Auto">
-        <TextBlock Grid.Column="0"
-                   Classes="meta"
-                   Text="{Binding Task.CreatedAtFormatted}"
-                   HorizontalAlignment="Center"
-                   VerticalAlignment="Center"/>
-        <Button Grid.Column="1" Classes="icon-btn"
-                Command="{Binding CloseDetailsCommand}"
-                ToolTip.Tip="{loc:Tr details.closeTip}"
-                VerticalAlignment="Center">
-          <PathIcon Data="{StaticResource Icon.X}" Width="14" Height="14"/>
-        </Button>
-      </Grid>
-    </Border>
-
     <!-- ── Header (sticky top): id · title · trash/skull · gear — task detail only ── -->
     <Border DockPanel.Dock="Top" Classes="island-header"
             IsVisible="{Binding IsTaskDetailVisible}">

src/ClaudeDo.Ui/Views/Islands/ListsIslandView.axaml

@@ -103,7 +103,6 @@
                   <PathIcon Grid.Column="0" Classes="list-icon"
                             Width="14" Height="14"
                             Data="{Binding IconKey, Converter={StaticResource IconKey}}"
-                            Foreground="{DynamicResource TextMuteBrush}"
                             HorizontalAlignment="Center" VerticalAlignment="Center"/>
                   <!-- Name -->
                   <TextBlock Grid.Column="1" Classes="list-label"
@@ -177,11 +176,11 @@
                             HorizontalAlignment="Left" VerticalAlignment="Center"
                             Margin="-8,0,0,0"/>
                   </Border>
-                  <!-- Color dot (6px circle, color from DotColorKey) -->
-                  <Ellipse Grid.Column="0"
-                           Width="6" Height="6"
-                           Fill="{Binding DotColorKey, Converter={StaticResource DotBrush}}"
-                           HorizontalAlignment="Center" VerticalAlignment="Center"/>
+                  <!-- Icon (list-settings → Icon tab; "Folder" when unset) -->
+                  <PathIcon Grid.Column="0" Classes="list-icon"
+                            Width="14" Height="14"
+                            Data="{Binding IconKey, Converter={StaticResource IconKey}}"
+                            HorizontalAlignment="Center" VerticalAlignment="Center"/>
                   <!-- Name -->
                   <TextBlock Grid.Column="1" Classes="list-label"
                              Text="{Binding Name}"