feat(ui): coloured dots for icon-less lists, guide line under chevron

Lists without an icon show a dot in a stable identity colour (same
palette/hash as Mission Control tiles); "Dot" is the new picker default.

src/ClaudeDo.Ui/Design/IslandStyles.axaml

@@ -54,6 +54,9 @@
          The old stroke version filled into a solid slab. -->
     <StreamGeometry x:Key="Icon.Inbox">F0 M3 5 H21 V19 H3 Z M5 7 H19 V12 H5 Z M5 14 H19 V17 H5 Z M11 7.6 H13 V9.4 H15 L12 12 L9 9.4 H11 Z</StreamGeometry>
 
+    <!-- Icon.Dot — picker preview for "no icon"; the sidebar renders it as a coloured Ellipse instead. -->
+    <StreamGeometry x:Key="Icon.Dot">M12 7a5 5 0 1 0 0 10a5 5 0 1 0 0-10z</StreamGeometry>
+
     <!-- Icon.Folder -->
     <StreamGeometry x:Key="Icon.Folder">M3 7a2 2 0 0 1 2-2h4l2 2h8a2 2 0 0 1 2 2v9a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2z</StreamGeometry>
 

src/ClaudeDo.Ui/ViewModels/Islands/ListNavItemViewModel.cs

@@ -1,4 +1,5 @@
 using ClaudeDo.Data.Models;
+using ClaudeDo.Ui.ViewModels.MissionControl;
 using CommunityToolkit.Mvvm.ComponentModel;
 
 namespace ClaudeDo.Ui.ViewModels.Islands;
@@ -30,7 +31,15 @@ public sealed partial class ListNavItemViewModel : ViewModelBase
     // DropHintAbove/Below, which mark an insertion point for list reordering.
     [ObservableProperty] private bool _isTaskDropTarget;
     // Settable (not init) so a list-settings icon change refreshes the row in place.
-    [ObservableProperty] private string? _iconKey;
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(IsDot))]
+    private string? _iconKey;
+
+    /// <summary>No icon picked — the row shows a coloured dot instead of a glyph.</summary>
+    public bool IsDot => IconKey is null or ListsIslandViewModel.ListIcon;
+
+    /// <summary>Identity colour of the dot, stable per list id across restarts.</summary>
+    public string DotColorKey => $"Identity{ConPtyPaneViewModel.StableIndex(Id, 6) + 1}";
     // The sidebar folder this row sits in (ListEntity.FolderId); null = top level.
     [ObservableProperty] private string? _folderId;
 }

src/ClaudeDo.Ui/ViewModels/MissionControl/ConPtyPaneViewModel.cs

@@ -30,7 +30,8 @@ public sealed partial class ConPtyPaneViewModel : ViewModelBase, IDisposable
 
     // FNV-1a, not string.GetHashCode: the latter is randomized per process, so the same task would
     // change colour on every app start.
-    private static int StableIndex(string value, int buckets)
+    /// <summary>Process-stable bucket for <paramref name="value"/>; also colours the sidebar list dots.</summary>
+    internal static int StableIndex(string value, int buckets)
     {
         uint hash = 2166136261;
         foreach (var c in value)

src/ClaudeDo.Ui/ViewModels/Modals/ListSettingsModalViewModel.cs

@@ -111,7 +111,7 @@ public sealed partial class ListSettingsModalViewModel : ViewModelBase
 
     public ObservableCollection<string> CommitTypeOptions { get; } = new(CommitTypeRegistry.Types);
 
-    public const string DefaultIcon = "Text";
+    public const string DefaultIcon = "Dot";
 
     /// <summary>Default icon for folders, kept apart from <see cref="DefaultIcon"/> so lists never look like folders.</summary>
     public const string DefaultFolderIcon = "Folder";
@@ -123,7 +123,7 @@ public sealed partial class ListSettingsModalViewModel : ViewModelBase
     public static readonly string[] IconOptions =
     [
         // general
-        "Folder", "Star", "Sun", "Calendar", "Clock", "Inbox", "Mail", "Text", "Search", "Grid",
+        "Dot", "Folder", "Star", "Sun", "Calendar", "Clock", "Inbox", "Mail", "Text", "Search", "Grid",
         // dev
         "Code", "Terminal", "Database", "Server", "Chip", "Bolt", "Wand", "Flask", "Shield",
         // status / flow

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

@@ -73,9 +73,12 @@
             </Border>
             <!-- Icon (list-settings → Icon tab; "Folder" when unset) -->
             <PathIcon Grid.Column="1" Classes="list-icon"
-                      Width="14" Height="14"
+                      Width="14" Height="14" IsVisible="{Binding !IsDot}"
                       Data="{Binding IconKey, Converter={StaticResource IconKey}}"
                       HorizontalAlignment="Center" VerticalAlignment="Center"/>
+            <Ellipse Grid.Column="1" Width="8" Height="8" IsVisible="{Binding IsDot}"
+                     Fill="{Binding DotColorKey, Converter={StaticResource DotBrush}}"
+                     HorizontalAlignment="Center" VerticalAlignment="Center"/>
             <!-- Name -->
             <TextBlock Grid.Column="2" Classes="list-label"
                        Text="{Binding Name}" ToolTip.Tip="{Binding Name}"
@@ -141,10 +144,9 @@
             </Grid>
           </Border>
 
-          <!-- Guide line drops from under the folder icon's centre (padding 10 + chevron 12 + half
-               of the 20px icon slot); children indent one icon slot past it. -->
+          <!-- Guide line drops from under the chevron's centre (padding 10 + half the 9px glyph). -->
           <Panel IsVisible="{Binding !IsCollapsed}">
-            <Border Width="1" HorizontalAlignment="Left" Margin="31,0,0,4"
+            <Border Width="1" HorizontalAlignment="Left" Margin="14,0,0,4"
                     Background="{DynamicResource LineBrush}" IsHitTestVisible="False"/>
             <ItemsControl ItemsSource="{Binding Children}" Margin="20,0,0,0"/>
           </Panel>