style(ui): Material Design icons for shared controls and modals

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/ClaudeDo.Ui/Views/Modals/DiffViewerView.axaml

@@ -45,7 +45,7 @@
         <ToggleButton Classes="icon-btn" IsChecked="{Binding WrapLines}"
                       VerticalAlignment="Center"
                       ToolTip.Tip="{loc:Tr modals.diff.wrapLines}">
-          <PathIcon Data="{StaticResource Icon.Wrap}" Width="14" Height="14"/>
+          <PathIcon Data="{Binding Source='mdi:Wrap', Converter={StaticResource IconKey}}" Width="14" Height="14"/>
         </ToggleButton>
         <ctl:OperationIndicator Status="{Binding ParseOp}"/>
       </StackPanel>

src/ClaudeDo.Ui/Views/Modals/SettingsModalView.axaml

@@ -349,10 +349,12 @@
                           <TextBlock Classes="meta" Grid.Column="3" Text="{Binding LastRunLabel}" VerticalAlignment="Center"
                                      TextTrimming="CharacterEllipsis"
                                      ToolTip.Tip="{Binding LastRunLabel}"/>
-                          <Button Classes="icon-btn" Grid.Column="4" Content="✕"
+                          <Button Classes="icon-btn" Grid.Column="4"
                                   ToolTip.Tip="{loc:Tr settings.prime.removeScheduleTip}"
                                   Command="{Binding $parent[ItemsControl].((vm:SettingsModalViewModel)DataContext).Prime.RemoveScheduleCommand}"
-                                  CommandParameter="{Binding}"/>
+                                  CommandParameter="{Binding}">
+                                  <PathIcon Width="12" Height="12" Data="{Binding Source='mdi:Close', Converter={StaticResource IconKey}}"/>
+                          </Button>
                         </Grid>
                         <TextBlock Classes="field-label" Text="{loc:Tr settings.prime.actionLabel}"/>
                         <StackPanel Orientation="Horizontal" Spacing="16">

src/ClaudeDo.Ui/Views/Modals/UsageMonitorModalView.axaml

@@ -25,10 +25,12 @@
       <StackPanel Orientation="Horizontal" Spacing="6">
         <Ellipse Classes="spinner" Width="12" Height="12" VerticalAlignment="Center"
                  IsVisible="{Binding IsRefreshing}"/>
-        <Button Classes="icon-btn" Content="⟳" FontSize="{DynamicResource FontSizeBody}"
+        <Button Classes="icon-btn" 
                 Command="{Binding RefreshCommand}"
                 IsEnabled="{Binding !IsRefreshing}"
-                ToolTip.Tip="{loc:Tr modals.usageMonitor.refreshHint}"/>
+                ToolTip.Tip="{loc:Tr modals.usageMonitor.refreshHint}">
+          <PathIcon Width="14" Height="14" Data="{Binding Source='mdi:Refresh', Converter={StaticResource IconKey}}"/>
+        </Button>
       </StackPanel>
     </ctl:ModalShell.HeaderActions>
     <DockPanel>