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

tests/HSchool.AppHost.Tests/PortraitApiTests.cs

@@ -107,7 +107,12 @@ public class PortraitApiTests(AppHostFixture fixture)
 
     private sealed record PersonListItem(string Id);
 
-    private sealed record PersonCardResponse(string Id, bool HasAvatar, bool HasHalfBody, bool HasFullBody);
+    private sealed record PersonCardResponse(
+        string Id,
+        bool HasAvatar,
+        bool HasCustom,
+        bool HasFullBody,
+        string? CustomPortraitPrompt);
 
     private sealed record SavesDirectoryResponse(string Path);
 }

tests/HSchool.Server.Tests/PortraitPromptBuilderTests.cs

@@ -43,19 +43,26 @@ public class PortraitPromptBuilderTests
     }
 
     [Fact]
-    public void Build_HalfBody_AddsHalfBodyPreset()
+    public void Build_Custom_UsesPromptExtraInsteadOfPreset()
     {
         var settings = new SwarmUiSettings
         {
             Positive = "School photo.",
-            HalfBody = new SwarmUiSettings.SwarmUiPreset { Positive = "Waist-up portrait." },
+            Avatar = new SwarmUiSettings.SwarmUiPreset { Positive = "Head and shoulders." },
             FullBody = new SwarmUiSettings.SwarmUiPreset { Positive = "Standing full body." },
         };
 
-        var (halfPositive, _) = PortraitPromptBuilder.Build(SampleCard(), settings, PortraitKind.Half);
+        const string extra = "standing in a school hallway, soft window light";
+        var (customPositive, _) = PortraitPromptBuilder.Build(
+            SampleCard(),
+            settings,
+            PortraitKind.Custom,
+            extra);
 
-        Assert.Contains("Waist-up portrait.", halfPositive, StringComparison.Ordinal);
-        Assert.DoesNotContain("Standing full body.", halfPositive, StringComparison.Ordinal);
+        Assert.Contains("School photo.", customPositive, StringComparison.Ordinal);
+        Assert.Contains(extra, customPositive, StringComparison.Ordinal);
+        Assert.DoesNotContain("Head and shoulders.", customPositive, StringComparison.Ordinal);
+        Assert.DoesNotContain("Standing full body.", customPositive, StringComparison.Ordinal);
     }
 
     private static PersonCardResponse SampleCard() =>