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

tests/CBDD.Tests/IndexDirectionTests.cs

@@ -14,6 +14,9 @@ public class IndexDirectionTests : IDisposable
 
     private readonly Shared.TestDbContext _db;
 
+    /// <summary>
+    /// Initializes database state for index direction tests.
+    /// </summary>
     public IndexDirectionTests()
     {
         if (File.Exists(_dbPath)) File.Delete(_dbPath);
@@ -21,12 +24,18 @@ public class IndexDirectionTests : IDisposable
         // _db.Database.EnsureCreated(); // Not needed/doesn't exist? StorageEngine handles creation.
     }
 
+    /// <summary>
+    /// Disposes test resources and deletes temporary files.
+    /// </summary>
     public void Dispose()
     {
         _db.Dispose();
         if (File.Exists(_dbPath)) File.Delete(_dbPath);
     }
 
+    /// <summary>
+    /// Verifies forward range scans return values in ascending order.
+    /// </summary>
     [Fact]
     public void Range_Forward_ReturnsOrderedResults()
     {
@@ -45,6 +54,9 @@ public class IndexDirectionTests : IDisposable
         collection.FindByLocation(results.Last())!.Age.ShouldBe(20);  // Last is 20
     }
 
+    /// <summary>
+    /// Verifies backward range scans return values in descending order.
+    /// </summary>
     [Fact]
     public void Range_Backward_ReturnsReverseOrderedResults()
     {
@@ -63,6 +75,9 @@ public class IndexDirectionTests : IDisposable
         collection.FindByLocation(results.Last())!.Age.ShouldBe(10);  // Last is 10
     }
 
+    /// <summary>
+    /// Verifies backward scans across split index pages return complete result sets.
+    /// </summary>
     [Fact]
     public void Range_Backward_WithMultiplePages_ReturnsReverseOrderedResults()
     {