fix: stop restoring soft-deleted mails during sync — they stay deleted

- Removed restore logic from imap_sync_account and imap_sync_folder
- Soft-deleted mails are now skipped during sync (not touched, not restored)
- This prevents deleted mails from reappearing when they are found on IMAP
- The sync queue handles retrying failed IMAP deletes

app/plugins/builtins/mail/services.py

@@ -636,8 +636,9 @@ async def imap_sync_folder(
             ).scalar_one_or_none()
 
             if existing_mail:
+                # Don't touch soft-deleted mails — they're being deleted via sync queue
                 if existing_mail.deleted_at is not None:
-                    existing_mail.deleted_at = None
+                    continue
                 continue
 
             # Fetch and parse the email
@@ -1124,10 +1125,9 @@ async def imap_sync_account(
                         ).scalar_one_or_none()
 
                     if existing_mail:
-                        # Restore soft-deleted mails if they still exist on IMAP
+                        # Don't touch soft-deleted mails — they're being deleted via sync queue
                         if existing_mail.deleted_at is not None:
-                            existing_mail.deleted_at = None
-                            logger.info("imap_sync: restored soft-deleted mail %s (still on IMAP)", existing_mail.id)
+                            continue
                         # Track folder moves: update folder_id and imap_uid if the
                         # mail now appears in a different IMAP folder.
                         if existing_mail.folder_id != folder.id: