fix: non-blocking relay publishes in send_nostr_dm (#3925)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Vlad Stan <stan.v.vlad@gmail.com>

lnbits/core/services/notifications.py

@@ -74,7 +74,7 @@ async def send_admin_notification(
     message: str,
     message_type: str | None = None,
 ) -> None:
-    return await send_notification(
+    return await send_notification_in_background(
         settings.lnbits_telegram_notifications_chat_id,
         settings.lnbits_nostr_notifications_identifiers,
         settings.lnbits_email_notifications_to_emails,
@@ -97,7 +97,7 @@ async def send_user_notification(
         if user_notifications.nostr_identifier
         else []
     )
-    return await send_notification(
+    return await send_notification_in_background(
         user_notifications.telegram_chat_id,
         nostr_identifiers,
         email_address,
@@ -302,6 +302,27 @@ def send_payment_notification_in_background(wallet: Wallet, payment: Payment):
         logger.warning(f"Error sending payment notification: {e}")
 
 
+async def send_notification_in_background(
+    telegram_chat_id: str | None,
+    nostr_identifiers: list[str] | None,
+    email_addresses: list[str] | None,
+    message: str,
+    message_type: str | None = None,
+):
+    try:
+        create_task(
+            send_notification(
+                telegram_chat_id,
+                nostr_identifiers,
+                email_addresses,
+                message,
+                message_type,
+            )
+        )
+    except Exception as e:
+        logger.warning(f"Error sending notification in background: {e}")
+
+
 async def send_ws_payment_notification(wallet: Wallet, payment: Payment):
     # TODO: websocket message should be a clean payment model
     # await websocket_manager.send(wallet.inkey, payment.json())