feat(email): export send attempt metadata

Add content-free provider delivery history to encrypted and daily owner exports, exclude payload hashes, and lock in tenant-safe hard-delete cascades.

JobTrackerApi.Tests/BackupControllerTests.cs

@@ -35,7 +35,22 @@ public sealed class BackupControllerTests
     {
         await using var db = CreateDb();
         db.Companies.Add(new Company { Name = "Acme", OwnerUserId = "user-1" });
-        db.JobApplications.Add(new JobApplication { JobTitle = "Backend Developer", OwnerUserId = "user-1" });
+        var job = new JobApplication { JobTitle = "Backend Developer", OwnerUserId = "user-1" };
+        db.JobApplications.Add(job);
+        await db.SaveChangesAsync();
+        db.EmailSendAttempts.Add(new EmailSendAttempt
+        {
+            Id = Guid.NewGuid(),
+            OwnerUserId = "user-1",
+            JobApplicationId = job.Id,
+            Provider = "gmail",
+            ClientRequestId = Guid.NewGuid().ToString(),
+            PayloadHash = new string('a', 64),
+            Status = EmailSendStatuses.Sent,
+            ProviderMessageId = "synthetic-message-id",
+            CreatedAtUtc = DateTime.UtcNow,
+            CompletedAtUtc = DateTime.UtcNow,
+        });
         await db.SaveChangesAsync();
 
         var provider = DataProtectionProvider.Create(new DirectoryInfo(Path.Combine(Path.GetTempPath(), $"jobtracker-tests-{Guid.NewGuid():N}")));
@@ -47,6 +62,14 @@ public sealed class BackupControllerTests
         Assert.Equal("application/octet-stream", file.ContentType);
         Assert.EndsWith(".jtbackup", file.FileDownloadName);
         Assert.NotEmpty(file.FileContents);
+
+        var protectedText = System.Text.Encoding.UTF8.GetString(file.FileContents);
+        var json = Convert.FromBase64String(provider.CreateProtector("JobTrackerApi.Backup.v1").Unprotect(protectedText));
+        using var document = System.Text.Json.JsonDocument.Parse(json);
+        var attempt = Assert.Single(document.RootElement.GetProperty("Data").GetProperty("EmailSendAttempts").EnumerateArray());
+        Assert.Equal("gmail", attempt.GetProperty("Provider").GetString());
+        Assert.Equal("sent", attempt.GetProperty("Status").GetString());
+        Assert.False(attempt.TryGetProperty("PayloadHash", out _));
     }
 
     private static JobTrackerContext CreateDb()