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

tests/CBDD.Tests/WalIndexTests.cs

@@ -18,6 +18,10 @@ public class WalIndexTests : IDisposable
     private readonly Shared.TestDbContext _db;
     private readonly ITestOutputHelper _output;
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="WalIndexTests"/> class.
+    /// </summary>
+    /// <param name="output">Test output sink.</param>
     public WalIndexTests(ITestOutputHelper output)
     {
         _output = output;
@@ -28,6 +32,9 @@ public class WalIndexTests : IDisposable
         _db = new Shared.TestDbContext(_dbPath);
     }
 
+    /// <summary>
+    /// Verifies index writes are recorded in the WAL.
+    /// </summary>
     [Fact]
     public void IndexWritesAreLoggedToWal()
     {
@@ -87,6 +94,9 @@ public class WalIndexTests : IDisposable
         return (PageType)pageData[4]; // Casting byte to PageType
     }
 
+    /// <summary>
+    /// Verifies offline compaction leaves the WAL empty.
+    /// </summary>
     [Fact]
     public void Compact_ShouldLeaveWalEmpty_AfterOfflineRun()
     {
@@ -110,6 +120,9 @@ public class WalIndexTests : IDisposable
         new FileInfo(_walPath).Length.ShouldBe(0);
     }
 
+    /// <summary>
+    /// Verifies WAL recovery followed by compaction preserves data.
+    /// </summary>
     [Fact]
     public void Recover_WithCommittedWal_ThenCompact_ShouldPreserveData()
     {
@@ -153,6 +166,9 @@ public class WalIndexTests : IDisposable
         }
     }
 
+    /// <summary>
+    /// Releases test resources.
+    /// </summary>
     public void Dispose()
     {
         try