Fix audit findings for coverage, architecture checks, and XML docs

tests/CBDD.Tests/DocumentCollectionIndexApiTests.cs

@@ -8,12 +8,18 @@ public class DocumentCollectionIndexApiTests : IDisposable
     private readonly string _dbPath;
     private readonly Shared.TestDbContext _db;
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="DocumentCollectionIndexApiTests"/> class.
+    /// </summary>
     public DocumentCollectionIndexApiTests()
     {
         _dbPath = Path.Combine(Path.GetTempPath(), $"collection_index_api_{Guid.NewGuid():N}.db");
         _db = new Shared.TestDbContext(_dbPath);
     }
 
+    /// <summary>
+    /// Verifies vector index creation and deletion behavior.
+    /// </summary>
     [Fact]
     public void CreateVectorIndex_And_DropIndex_Should_Work()
     {
@@ -32,6 +38,9 @@ public class DocumentCollectionIndexApiTests : IDisposable
         _db.VectorItems.GetIndexes().Select(x => x.Name).ShouldNotContain("idx_vector_extra");
     }
 
+    /// <summary>
+    /// Verifies ensure-index returns existing indexes when already present.
+    /// </summary>
     [Fact]
     public void EnsureIndex_Should_Return_Existing_Index_When_Already_Present()
     {
@@ -41,12 +50,18 @@ public class DocumentCollectionIndexApiTests : IDisposable
         ReferenceEquals(first, second).ShouldBeTrue();
     }
 
+    /// <summary>
+    /// Verifies dropping the primary index name is rejected.
+    /// </summary>
     [Fact]
     public void DropIndex_Should_Reject_Primary_Index_Name()
     {
         Should.Throw<InvalidOperationException>(() => _db.People.DropIndex("_id"));
     }
 
+    /// <summary>
+    /// Disposes test resources and removes temporary files.
+    /// </summary>
     public void Dispose()
     {
         _db.Dispose();