fix(transaction): preserve primary failures

Keep action and commit exceptions when rollback fails; clear owned transaction state and cover the lifecycle with SQLite tests.

Ref: IT-1588

HrynCo.DAL.EF.Tests/TransactionFailureInterceptor.cs

@@ -0,0 +1,42 @@
+namespace HrynCo.DAL.EF.Tests;
+
+using System.Data.Common;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+
+internal sealed class TransactionFailureInterceptor : DbTransactionInterceptor
+{
+    public Exception? CommitException { get; init; }
+    public Exception? RollbackException { get; init; }
+    public int CommitAttempts { get; private set; }
+    public int RollbackAttempts { get; private set; }
+
+    public override ValueTask<InterceptionResult> TransactionCommittingAsync(
+        DbTransaction transaction,
+        TransactionEventData eventData,
+        InterceptionResult result,
+        CancellationToken cancellationToken = default)
+    {
+        CommitAttempts++;
+        if (CommitException is not null)
+        {
+            throw CommitException;
+        }
+
+        return ValueTask.FromResult(result);
+    }
+
+    public override ValueTask<InterceptionResult> TransactionRollingBackAsync(
+        DbTransaction transaction,
+        TransactionEventData eventData,
+        InterceptionResult result,
+        CancellationToken cancellationToken = default)
+    {
+        RollbackAttempts++;
+        if (RollbackException is not null)
+        {
+            throw RollbackException;
+        }
+
+        return ValueTask.FromResult(result);
+    }
+}