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

tests/CBDD.Tests/DbContextTests.cs

@@ -12,11 +12,17 @@ public class DbContextTests : IDisposable
 {
     private string _dbPath;
 
+    /// <summary>
+    /// Initializes test file paths for database context tests.
+    /// </summary>
     public DbContextTests()
     {
         _dbPath = Path.Combine(Path.GetTempPath(), $"test_dbcontext_{Guid.NewGuid()}.db");
     }
 
+    /// <summary>
+    /// Verifies the basic database context lifecycle works.
+    /// </summary>
     [Fact]
     public void DbContext_BasicLifecycle_Works()
     {
@@ -31,6 +37,9 @@ public class DbContextTests : IDisposable
         found.Age.ShouldBe(30);
     }
 
+    /// <summary>
+    /// Verifies multiple CRUD operations execute correctly in one context.
+    /// </summary>
     [Fact]
     public void DbContext_MultipleOperations_Work()
     {
@@ -59,6 +68,9 @@ public class DbContextTests : IDisposable
         db.Users.Count().ShouldBe(1);
     }
 
+    /// <summary>
+    /// Verifies disposing and reopening context preserves persisted data.
+    /// </summary>
     [Fact]
     public void DbContext_Dispose_ReleasesResources()
     {
@@ -90,6 +102,9 @@ public class DbContextTests : IDisposable
         return Convert.ToHexString(sha256.ComputeHash(stream));
     }
 
+    /// <summary>
+    /// Verifies database file size and content change after insert and checkpoint.
+    /// </summary>
     [Fact]
     public void DatabaseFile_SizeAndContent_ChangeAfterInsert()
     {
@@ -117,6 +132,9 @@ public class DbContextTests : IDisposable
         afterInsertHash.ShouldNotBe(initialHash);
     }
 
+    /// <summary>
+    /// Verifies the WAL file path is auto-derived from database path.
+    /// </summary>
     [Fact]
     public void DbContext_AutoDerivesWalPath()
     {
@@ -127,6 +145,9 @@ public class DbContextTests : IDisposable
         File.Exists(walPath).ShouldBeTrue();
     }
 
+    /// <summary>
+    /// Verifies custom page file and compression options support roundtrip data access.
+    /// </summary>
     [Fact]
     public void DbContext_WithCustomPageFileAndCompressionOptions_ShouldSupportRoundTrip()
     {
@@ -165,6 +186,9 @@ public class DbContextTests : IDisposable
         }
     }
 
+    /// <summary>
+    /// Verifies compact API returns stats and preserves data consistency.
+    /// </summary>
     [Fact]
     public void DbContext_CompactApi_ShouldReturnStatsAndPreserveData()
     {
@@ -197,6 +221,9 @@ public class DbContextTests : IDisposable
         }
     }
 
+    /// <summary>
+    /// Disposes test resources and cleans up generated files.
+    /// </summary>
     public void Dispose()
     {
         try