feat(viewer-repo): add LoadForMatchContextAsync for battle-node ctx build

Focused AsNoTracking load with Info.SelectedEmblem/SelectedDegree includes
for the new MatchContextBuilder. Single test locks the include graph.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.Database/Repositories/Viewer/IViewerRepository.cs

@@ -20,4 +20,11 @@ public interface IViewerRepository
     /// viewer's UDID to the target, then deletes the anonymous viewer.
     /// </summary>
     Task MergeAnonymousViewerInto(long anonymousViewerId, long targetViewerId);
+
+    /// <summary>
+    /// Focused load for building a battle-node <c>MatchContext</c>: viewer + Info + Info's
+    /// equipped Emblem/Degree nav refs. Read-only (AsNoTracking). Returns null if the viewer
+    /// doesn't exist.
+    /// </summary>
+    Task<Models.Viewer?> LoadForMatchContextAsync(long viewerId);
 }

SVSim.Database/Repositories/Viewer/ViewerRepository.cs

@@ -228,6 +228,15 @@ public class ViewerRepository : IViewerRepository
         await _dbContext.SaveChangesAsync();
     }
 
+    public async Task<Models.Viewer?> LoadForMatchContextAsync(long viewerId)
+    {
+        return await _dbContext.Set<Models.Viewer>()
+            .AsNoTracking()
+            .Include(v => v.Info.SelectedEmblem)
+            .Include(v => v.Info.SelectedDegree)
+            .FirstOrDefaultAsync(v => v.Id == viewerId);
+    }
+
     private async Task<Models.Viewer> BuildDefaultViewer(string displayName, int initialTutorialState = 1)
     {
         Models.Viewer viewer = new Models.Viewer

SVSim.UnitTests/Repositories/ViewerRepositoryMatchContextTests.cs

@@ -0,0 +1,50 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Database;
+using SVSim.Database.Models;
+using SVSim.Database.Repositories.Viewer;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Repositories;
+
+[TestFixture]
+public class ViewerRepositoryMatchContextTests
+{
+    [Test]
+    public async Task LoadForMatchContext_includes_info_selected_emblem_and_degree()
+    {
+        await using var factory = new SVSimTestFactory();
+        var vid = await factory.SeedViewerAsync();
+
+        int emblemId, degreeId;
+        using (var seedScope = factory.Services.CreateScope())
+        {
+            var db = seedScope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+            // Use existing rows from the reference-data seed — inserting EmblemEntry/DegreeEntry
+            // with a hardcoded Id collides with the seeded catalog (UNIQUE constraint).
+            var emblem = await db.Emblems.FirstAsync();
+            var degree = await db.Degrees.FirstAsync();
+            emblemId = emblem.Id;
+            degreeId = degree.Id;
+
+            var viewer = await db.Viewers.FindAsync(vid);
+            viewer!.Info.CountryCode = "KOR";
+            viewer.Info.IsOfficial = true;
+            viewer.Info.SelectedEmblem = emblem;
+            viewer.Info.SelectedDegree = degree;
+            viewer.DisplayName = "DraftedPlayer";
+            await db.SaveChangesAsync();
+        }
+
+        using var scope = factory.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<IViewerRepository>();
+        var loaded = await repo.LoadForMatchContextAsync(vid);
+
+        Assert.That(loaded, Is.Not.Null);
+        Assert.That(loaded!.DisplayName, Is.EqualTo("DraftedPlayer"));
+        Assert.That(loaded.Info.CountryCode, Is.EqualTo("KOR"));
+        Assert.That(loaded.Info.IsOfficial, Is.True);
+        Assert.That(loaded.Info.SelectedEmblem.Id, Is.EqualTo(emblemId));
+        Assert.That(loaded.Info.SelectedDegree.Id, Is.EqualTo(degreeId));
+    }
+}