feat(ui): add ThemedDatePicker control and adopt in Prime settings

New themed picker supports single-date, date+time, and range modes
(replaces inconsistent CalendarDatePicker / DatePicker / TimePicker
visuals). Used in the Prime schedules row to combine StartDate /
EndDate into a single range picker.

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

src/ClaudeDo.Ui/Views/Controls/ThemedDatePicker.axaml

@@ -0,0 +1,167 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="ClaudeDo.Ui.Views.Controls.ThemedDatePicker"
+             x:Name="Root">
+
+  <UserControl.Styles>
+    <Style Selector="ToggleButton.trigger">
+      <Setter Property="Background" Value="{DynamicResource DeepBrush}"/>
+      <Setter Property="BorderBrush" Value="{DynamicResource LineBrush}"/>
+      <Setter Property="BorderThickness" Value="1"/>
+      <Setter Property="CornerRadius" Value="{StaticResource InputCornerRadius}"/>
+      <Setter Property="Padding" Value="10,6"/>
+      <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
+      <Setter Property="VerticalContentAlignment" Value="Center"/>
+      <Setter Property="Foreground" Value="{DynamicResource TextBrush}"/>
+      <Setter Property="MinHeight" Value="30"/>
+    </Style>
+    <Style Selector="ToggleButton.trigger:pointerover /template/ ContentPresenter">
+      <Setter Property="Background" Value="{DynamicResource Surface2Brush}"/>
+      <Setter Property="BorderBrush" Value="{DynamicResource LineBrightBrush}"/>
+    </Style>
+    <Style Selector="ToggleButton.trigger:checked /template/ ContentPresenter">
+      <Setter Property="Background" Value="{DynamicResource Surface2Brush}"/>
+      <Setter Property="BorderBrush" Value="{DynamicResource AccentBrush}"/>
+    </Style>
+
+    <Style Selector="Button.quick">
+      <Setter Property="Background" Value="{DynamicResource DeepBrush}"/>
+      <Setter Property="BorderBrush" Value="{DynamicResource LineBrush}"/>
+      <Setter Property="BorderThickness" Value="1"/>
+      <Setter Property="Foreground" Value="{DynamicResource TextDimBrush}"/>
+      <Setter Property="CornerRadius" Value="999"/>
+      <Setter Property="Padding" Value="10,3"/>
+      <Setter Property="FontSize" Value="11"/>
+      <Setter Property="MinHeight" Value="22"/>
+    </Style>
+    <Style Selector="Button.quick:pointerover /template/ ContentPresenter">
+      <Setter Property="Background" Value="{DynamicResource Surface3Brush}"/>
+      <Setter Property="BorderBrush" Value="{DynamicResource LineBrightBrush}"/>
+      <Setter Property="TextElement.Foreground" Value="{DynamicResource TextBrush}"/>
+    </Style>
+
+    <Style Selector="Button.nav">
+      <Setter Property="Background" Value="Transparent"/>
+      <Setter Property="BorderThickness" Value="0"/>
+      <Setter Property="Foreground" Value="{DynamicResource TextDimBrush}"/>
+      <Setter Property="Padding" Value="6,2"/>
+      <Setter Property="CornerRadius" Value="6"/>
+      <Setter Property="MinWidth" Value="28"/>
+    </Style>
+    <Style Selector="Button.nav:pointerover /template/ ContentPresenter">
+      <Setter Property="Background" Value="{DynamicResource Surface3Brush}"/>
+      <Setter Property="TextElement.Foreground" Value="{DynamicResource TextBrush}"/>
+    </Style>
+
+    <Style Selector="Button.day">
+      <Setter Property="Background" Value="Transparent"/>
+      <Setter Property="BorderBrush" Value="Transparent"/>
+      <Setter Property="BorderThickness" Value="1"/>
+      <Setter Property="Foreground" Value="{DynamicResource TextBrush}"/>
+      <Setter Property="Width" Value="32"/>
+      <Setter Property="Height" Value="32"/>
+      <Setter Property="CornerRadius" Value="999"/>
+      <Setter Property="FontSize" Value="12"/>
+      <Setter Property="HorizontalContentAlignment" Value="Center"/>
+      <Setter Property="VerticalContentAlignment" Value="Center"/>
+      <Setter Property="Padding" Value="0"/>
+    </Style>
+    <Style Selector="Button.day:pointerover /template/ ContentPresenter">
+      <Setter Property="Background" Value="{DynamicResource Surface3Brush}"/>
+    </Style>
+    <Style Selector="Button.day.outside">
+      <Setter Property="Foreground" Value="{DynamicResource TextFaintBrush}"/>
+    </Style>
+    <Style Selector="Button.day.today">
+      <Setter Property="BorderBrush" Value="{DynamicResource AccentBrush}"/>
+    </Style>
+    <Style Selector="Button.day.selected /template/ ContentPresenter">
+      <Setter Property="Background" Value="{DynamicResource AccentBrush}"/>
+      <Setter Property="TextElement.Foreground" Value="White"/>
+    </Style>
+    <Style Selector="Button.day.selected:pointerover /template/ ContentPresenter">
+      <Setter Property="Background" Value="{DynamicResource AccentDimBrush}"/>
+    </Style>
+
+    <Style Selector="TextBlock.weekday">
+      <Setter Property="HorizontalAlignment" Value="Center"/>
+      <Setter Property="Foreground" Value="{DynamicResource TextMuteBrush}"/>
+      <Setter Property="FontSize" Value="10"/>
+      <Setter Property="FontWeight" Value="SemiBold"/>
+    </Style>
+  </UserControl.Styles>
+
+  <Grid>
+    <ToggleButton x:Name="TriggerButton" Classes="trigger">
+      <Grid ColumnDefinitions="Auto,*,Auto">
+        <PathIcon Grid.Column="0" Width="14" Height="14"
+                  Margin="0,0,8,0"
+                  Foreground="{DynamicResource TextDimBrush}"
+                  Data="M19,4H18V2H16V4H8V2H6V4H5A2,2 0 0,0 3,6V20A2,2 0 0,0 5,22H19A2,2 0 0,0 21,20V6A2,2 0 0,0 19,4M19,20H5V10H19V20M19,8H5V6H19V8Z"/>
+        <TextBlock Grid.Column="1"
+                   Text="{Binding #Root.DisplayText}"
+                   Foreground="{Binding #Root.DisplayForeground}"
+                   VerticalAlignment="Center"
+                   TextTrimming="CharacterEllipsis"/>
+        <PathIcon Grid.Column="2" Width="10" Height="10"
+                  Margin="8,0,0,0"
+                  Foreground="{DynamicResource TextMuteBrush}"
+                  Data="M7,10L12,15L17,10H7Z"/>
+      </Grid>
+    </ToggleButton>
+
+    <Popup x:Name="PickerPopup"
+           PlacementTarget="{Binding #TriggerButton}"
+           Placement="Bottom"
+           IsOpen="{Binding #TriggerButton.IsChecked, Mode=TwoWay}"
+           IsLightDismissEnabled="True">
+      <Border Background="{DynamicResource Surface2Brush}"
+              BorderBrush="{DynamicResource LineBrush}"
+              BorderThickness="1"
+              CornerRadius="10"
+              Padding="14"
+              Margin="0,4,0,0"
+              BoxShadow="{StaticResource ModalShadow}"
+              MinWidth="300">
+        <StackPanel Spacing="10">
+          <StackPanel Orientation="Horizontal" Spacing="6">
+            <Button Classes="quick" Content="Today" Click="OnTodayClick"/>
+            <Button Classes="quick" Content="Tomorrow" Click="OnTomorrowClick"/>
+            <Button Classes="quick" Content="Next Mon" Click="OnNextMondayClick"/>
+            <Button Classes="quick" Content="Clear" Click="OnClearClick"/>
+          </StackPanel>
+
+          <Grid ColumnDefinitions="Auto,*,Auto" Margin="0,2,0,0">
+            <Button Grid.Column="0" Click="OnPrevMonthClick" Classes="nav" Content="◀"/>
+            <TextBlock Grid.Column="1" x:Name="MonthHeader"
+                       HorizontalAlignment="Center"
+                       VerticalAlignment="Center"
+                       FontWeight="SemiBold"
+                       FontSize="13"
+                       Foreground="{DynamicResource TextBrush}"/>
+            <Button Grid.Column="2" Click="OnNextMonthClick" Classes="nav" Content="▶"/>
+          </Grid>
+
+          <UniformGrid Columns="7" x:Name="WeekdayHeaders"/>
+
+          <UniformGrid Columns="7" Rows="6" x:Name="DayGrid"/>
+
+          <Grid x:Name="TimeRow"
+                ColumnDefinitions="Auto,*,Auto"
+                Margin="0,4,0,0">
+            <TextBlock Grid.Column="0" Text="Time"
+                       VerticalAlignment="Center"
+                       Foreground="{DynamicResource TextDimBrush}"
+                       Margin="0,0,8,0"/>
+            <TextBox Grid.Column="1" x:Name="TimeInput"
+                     Watermark="HH:mm" MaxLength="5"
+                     Text="{Binding #Root.TimeText, Mode=TwoWay}"/>
+            <Button Grid.Column="2" Content="Done"
+                    Click="OnDoneClick"
+                    Margin="8,0,0,0"/>
+          </Grid>
+        </StackPanel>
+      </Border>
+    </Popup>
+  </Grid>
+</UserControl>