feat: inline unsubscribe button on email rows

- ✉✕ button appears on rows where the email has a List-Unsubscribe header
- One-click POST / HTTP GET executed automatically; shows ✓ on success
- mailto: targets open the user mail client (we never auto-send email)
- POST /email/{id}/unsubscribe: detects sender, then processes — UserId scoped
- EmailSummaryDto gains IsStarred, HasListUnsubscribe, SupportsOneClick fields
- Both SearchService and CleanupService updated to populate new DTO fields

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/InboxIntel.Infrastructure/Search/SearchService.cs

@@ -70,7 +70,8 @@ public class SearchService : ISearchService
             .Select(e => new EmailSummaryDto(
                 e.Id, e.GmailMessageId, e.Subject, e.Snippet,
                 e.Sender!.Address, e.Sender.DisplayName, e.SentAtUtc,
-                e.IsUnread, e.HasAttachments, e.SizeEstimateBytes, e.Category))
+                e.IsUnread, e.IsStarred, e.HasAttachments, e.SizeEstimateBytes, e.Category,
+                e.HasListUnsubscribe, e.SupportsOneClickUnsubscribe))
             .ToListAsync(ct);
 
         return new PagedResult<EmailSummaryDto>