test(blogs): configure SiteSettings.Blog in MappedClaimsBlogsWebServerFixture

BlogSpotService's constructor throws InvalidOperationException
("SiteSettings.Blog is not configured.") when IOptions<SiteSettings>.Blog
is null, so every request to BlogApiController 500'd resolving the
service — all 3 BlogApiMappedClaimsTests were failing with
InternalServerError.

The mapped-claims fixture never configured SiteSettings (the main
BlogsWebServerFixture does, pointing Blog at a per-run temp dir).
Mirror that: Configure<SiteSettings>(s => s.Blog = <temp dir>)
before AddScoped<BlogSpotService>(). These tests are JSON-only
(AttachFiles short-circuits), but the service must be constructible.

Verified: BlogApiMappedClaimsTests 3/3 green; full Yavsc.Blogs.Tests
37/37 green.

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

src/Yavsc.Blogs.Tests/BlogApiMappedClaimsTests.cs

@@ -74,7 +74,7 @@ IClassFixture<MappedClaimsBlogsWebServerFixture>
         var draft = new BlogPost
         {
             Id = 0,
-            Title = "Billet JWT remappe",
+            Title = "Billet JWT re-mappé",
             AuthorId = "payload-attacker",
             Article = "Contenu de test.",
             DateCreated = DateTime.UtcNow,

src/Yavsc.Blogs.Tests/Fixtures/MappedClaimsBlogsWebServerFixture.cs

@@ -39,6 +39,18 @@ public sealed class MappedClaimsBlogsWebServerFixture : IDisposable, IBackendFix
             opt.UseInMemoryDatabase("Yavsc.Blogs.Tests.MappedClaims", _inMemoryRoot));
 
         builder.Services.AddSingleton<IFileSystemAuthManager>(new NoopFileSystemAuthManager());
+
+        // BlogSpotService's constructor throws InvalidOperationException
+        // ("SiteSettings.Blog is not configured.") when Blog is null, so
+        // every request hitting BlogApiController would 500 resolving the
+        // service. These tests never upload files (JSON-only POST/PUT), so
+        // AttachFiles short-circuits — but the service still has to be
+        // constructible. Point Blog at a per-run temp directory, mirroring
+        // BlogsWebServerFixture.
+        builder.Services.Configure<SiteSettings>(s =>
+        {
+            s.Blog = Path.Combine(Path.GetTempPath(), "postit-blogs-mappedclaims-" + Guid.NewGuid().ToString("N"));
+        });
         builder.Services.AddScoped<BlogSpotService>();
         builder.Services.AddScoped<IAuthorizationHandler, PermissionHandler>();
         builder.Services.AddControllers()