Implement custom portrait generation: update API, UI, and localization to support user-defined prompts for portraits, replacing half-body option with custom variant.

src/HSchool.Server/Game/SwarmUiSettings.cs

@@ -25,14 +25,14 @@ internal sealed class SwarmUiSettings
 
     public SwarmUiPreset Avatar { get; init; } = new();
 
-    public SwarmUiPreset HalfBody { get; init; } = new();
+    public SwarmUiPreset Custom { get; init; } = new();
 
     public SwarmUiPreset FullBody { get; init; } = new();
 
     public SwarmUiPreset PresetFor(PortraitKind kind) => kind switch
     {
         PortraitKind.Avatar => Avatar,
-        PortraitKind.Half => HalfBody,
+        PortraitKind.Custom => Custom,
         PortraitKind.Full => FullBody,
         _ => throw new ArgumentOutOfRangeException(nameof(kind)),
     };