Fix: IMAP over SSL connected without TLS; never lose a sent message's copy

v1.3.26's IMAP4_SSL subclass put its create_client ahead of aioimaplib's,
which is where the TLS context is made — so port 993 got plain TCP, the
server waited for a handshake, and every SSL account timed out ("Can't
reach the mail server"). The context is now made in our create_client too,
and a test checks an SSL client really gets one (it fails without the fix).

With IMAP down, a send could still be delivered by SMTP while filing its copy
in Sent failed — the send then counted as done and the copy was lost. The
copy is now kept and filed by file_sent_copy_job, retried (arq Retry) for
about 24 hours, then shown in Sent as usual.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/workers/worker.py

@@ -15,7 +15,7 @@ from typing import Any
 from arq import func
 
 from app.outbox.draft_sync import push_draft_to_imap_job, remove_imap_draft_job
-from app.outbox.jobs import send_job
+from app.outbox.jobs import file_sent_copy_job, send_job
 from app.sync.actions import (
     ACTION_MAX_TRIES,
     delete_thread_job,
@@ -48,6 +48,7 @@ _RETRYING_ACTIONS: list[Any] = [
     restore_thread_job,
     delete_thread_job,
     empty_folder_job,
+    file_sent_copy_job,
 ]
 
 INTERACTIVE_FUNCTIONS: list[Any] = [