Two themes, and one place that decides what colour a station is

Colours came from static brushes scattered over the windows. They now come
from a Theme, and everything that paints a station, a spot or a log row
asks Themes.Current as it paints, so changing the theme changes every
window without reopening it.

light is N1MM's own palette, read out of ApplicationStyles: the pale blue
behind a window, ivory on a button, white boxes, and the four colours a
station is painted in. dark is the same states in colours for a dark
screen, which is roughly what the program looked like before.

Config > Manage Skins, Colors and Fonts picks one, under N1MM's name for
the same dialog, and shows what each theme paints a callsign. The choice
is kept in settings.json as Theme, and light is the default.

The window chrome follows through resources the Fluent controls read, so a
text box and a button take the theme's colours in every state. Fonts and
skins are not part of it.

Looked at under Xvfb in both themes: the entry window, the theme dialog,
and the log window with its rows still coloured by what each contact was
worth.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/Nonemm.App/Dialogs/ThemeDialog.axaml

@@ -0,0 +1,27 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:Class="Nonemm.App.Dialogs.ThemeDialog"
+        Title="Colors" Width="360" SizeToContent="Height"
+        WindowStartupLocation="CenterOwner" CanResize="False">
+  <DockPanel Margin="14">
+    <StackPanel DockPanel.Dock="Bottom" Orientation="Horizontal" HorizontalAlignment="Center"
+                Spacing="30" Margin="0,14,0,0">
+      <Button Content="Ok" Width="85" HorizontalContentAlignment="Center"
+              Click="OnOk" IsDefault="True" />
+      <Button Content="Cancel" Width="85" HorizontalContentAlignment="Center"
+              Click="OnCancel" IsCancel="True" />
+    </StackPanel>
+    <StackPanel Spacing="8">
+      <TextBlock Text="Colors" FontSize="11" />
+      <ComboBox Name="ThemeBox" HorizontalAlignment="Stretch" SelectionChanged="OnPicked" />
+      <TextBlock Name="AboutText" FontSize="11" TextWrapping="Wrap" />
+      <ItemsControl Name="Swatches" Margin="0,4,0,0">
+        <ItemsControl.ItemsPanel>
+          <ItemsPanelTemplate>
+            <WrapPanel />
+          </ItemsPanelTemplate>
+        </ItemsControl.ItemsPanel>
+      </ItemsControl>
+    </StackPanel>
+  </DockPanel>
+</Window>