feat(ui): use a 24h TimePicker for prime schedule time entry

Replace the free-text time TextBox (which silently reset bad input to 07:00)
with Avalonia's TimePicker (24-hour, 5-minute steps), making invalid times
impossible. Drops the now-unused TimeSpanToHhmmConverter.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ClaudeDo.Ui/Converters/TimeSpanToHhmmConverter.cs

@@ -1,21 +0,0 @@
-using System.Globalization;
-using Avalonia.Data.Converters;
-
-namespace ClaudeDo.Ui.Converters;
-
-public sealed class TimeSpanToHhmmConverter : IValueConverter
-{
-    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture) =>
-        value is TimeSpan t ? $"{t.Hours:00}:{t.Minutes:00}" : "07:00";
-
-    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
-    {
-        if (value is not string s) return new TimeSpan(7, 0, 0);
-        var parts = s.Split(':');
-        if (parts.Length == 2 &&
-            int.TryParse(parts[0], out var h) && h is >= 0 and <= 23 &&
-            int.TryParse(parts[1], out var m) && m is >= 0 and <= 59)
-            return new TimeSpan(h, m, 0);
-        return new TimeSpan(7, 0, 0);
-    }
-}

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

@@ -2,7 +2,6 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:vm="using:ClaudeDo.Ui.ViewModels.Modals"
         xmlns:settings="using:ClaudeDo.Ui.ViewModels.Modals.Settings"
-        xmlns:conv="using:ClaudeDo.Ui.Converters"
         xmlns:ctl="using:ClaudeDo.Ui.Views.Controls"
         x:Class="ClaudeDo.Ui.Views.Modals.SettingsModalView"
         x:DataType="vm:SettingsModalViewModel"
@@ -19,9 +18,6 @@
     <KeyBinding Gesture="Escape" Command="{Binding CancelCommand}"/>
   </Window.KeyBindings>
 
-  <Window.Resources>
-    <conv:TimeSpanToHhmmConverter x:Key="TimeSpanToHhmm"/>
-  </Window.Resources>
 
   <ctl:ModalShell Title="SETTINGS" CloseCommand="{Binding CancelCommand}">
     <ctl:ModalShell.Footer>
@@ -198,8 +194,9 @@
                           <ToggleButton Classes="day-toggle" Content="Sa" IsChecked="{Binding Saturday, Mode=TwoWay}"/>
                           <ToggleButton Classes="day-toggle" Content="Su" IsChecked="{Binding Sunday, Mode=TwoWay}"/>
                         </StackPanel>
-                        <TextBox Grid.Column="2" Width="64"
+                        <TimePicker Grid.Column="2"
-                                 Text="{Binding TimeOfDay, Mode=TwoWay, Converter={StaticResource TimeSpanToHhmm}}"
+                                    SelectedTime="{Binding TimeOfDay, Mode=TwoWay}"
+                                    ClockIdentifier="24HourClock" MinuteIncrement="5"
                                     VerticalAlignment="Center"/>
                         <TextBlock Classes="meta" Grid.Column="3" Text="{Binding LastRunLabel}" VerticalAlignment="Center"
                                    MinWidth="80"/>