Bring the last three outlined marks over to the filled tile

ServerScreen, LockedScreen and PendingScreen were the only places left drawing
v1: a 44px square outlined in the accent with >_ in the accent inside it. Every
other place the mark appears — both headers, the desktop titlebar, the launcher
icon and the .ico — draws it filled.

The radius is derived rather than chosen. The mark is 6 at 20 and 8 at 26, a
third of a unit per unit of tile, which puts 44 at exactly 14 — and 14 is
already on Phone.axaml's radius ladder as the one for a block of monospaced
output, which is a fair description of a box with >_ in it.

PendingScreen takes the shape and not the colour. It is the screen that says a
surface is not built yet, and the accent is the shell's one "do this" colour; a
tile in Raised with the glyph left at TextFaint keeps the mark recognisable
while the screen goes on looking as inert as it is.

src/DodoSSH.Client.Android/Views/LockedScreen.axaml

@@ -24,10 +24,11 @@
 
       <!-- Identity. The chip names the account so a phone with two profiles is not a guess. -->
       <StackPanel Grid.Row="0" VerticalAlignment="Center" HorizontalAlignment="Center" Spacing="10" Margin="0,48,0,36">
-        <Border Width="44" Height="44" BorderBrush="{StaticResource Accent}" BorderThickness="1"
+        <!-- Filled since v2; see ServerScreen for where the 14 comes from. -->
+        <Border Width="44" Height="44" CornerRadius="14" Background="{StaticResource Accent}"
                 HorizontalAlignment="Center">
-          <TextBlock Text="&gt;_" Foreground="{StaticResource Accent}" FontFamily="{StaticResource MonoFont}"
-                     FontSize="16" FontWeight="SemiBold"
+          <TextBlock Text="&gt;_" Foreground="{StaticResource AccentInk}" FontFamily="{StaticResource MonoFont}"
+                     FontSize="16" FontWeight="Bold"
                      HorizontalAlignment="Center" VerticalAlignment="Center" />
         </Border>