feat: "Email sent" column and per-event copy-to-organizer BCC

Organizers had no way to see whether a ticket email went out short of
reading the Postfix journal, and no copy of what the attendee received —
LNbits submits over SMTP, so nothing lands in a Sent folder.

- Admin ticket table gains an "Email sent" column derived from
  `extra.email_notification_sent` ("✓ sent" / "not sent" / "unpaid" /
  "no email").
- `extra.copy_to_organizer`: BCC every ticket email to the event's
  reply-to address (explicit, else the owner's account email) on the SMTP
  envelope only — no Bcc/To header, and skipped when the buyer *is* that
  address. Toggle sits with the other delivery switches in the admin form.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EYwoAkZZmXMMmaBp4WGUBo

services.py

@@ -255,6 +255,13 @@ async def _deliver_ticket_notifications(
     if result.email.attempted:
         try:
             assert ticket.email
+            bcc = (
+                [reply_to]
+                if event.extra.copy_to_organizer
+                and reply_to
+                and reply_to.lower() != ticket.email.lower()
+                else []
+            )
             card = render_ticket_card(
                 ticket,
                 event,
@@ -271,6 +278,7 @@ async def _deliver_ticket_notifications(
                 ],
                 reply_to=reply_to,
                 sender_name=organizer_sender_name(event),
+                bcc=bcc,
             )
             ticket.extra.email_notification_sent = True
             result.email.sent = True
@@ -304,6 +312,7 @@ async def _send_ticket_email_notification(
     attachments: list[tuple[str, bytes]] | None = None,
     reply_to: str | None = None,
     sender_name: str | None = None,
+    bcc: list[str] | None = None,
 ) -> None:
     """Multipart (text + HTML) ticket email through the instance SMTP
     settings. Core's `send_email_notification` is plain-text only, which is
@@ -320,6 +329,10 @@ async def _send_ticket_email_notification(
     for address in to_emails:
         if not is_valid_email_address(address):
             raise ValueError(f"Invalid email address: {address}")
+    # BCC recipients ride only on the SMTP envelope, never in a header.
+    envelope_recipients = list(to_emails) + [
+        b for b in (bcc or []) if is_valid_email_address(b)
+    ]
 
     msg = build_ticket_email(
         from_email,
@@ -339,7 +352,7 @@ async def _send_ticket_email_notification(
         username,
         settings.lnbits_email_notifications_password,
         from_email,
-        to_emails,
+        envelope_recipients,
         msg.as_string(),
     )