feat: Add Telegram chat ID to ShopModel for automatic invoice sending

chore: Update Dockerfile to install WeasyPrint dependencies

feat: Enhance ShopOrderModelAdmin with invoice download buttons

feat: Implement invoice generation for OrderModel and ShopOrderModel

feat: Send invoice to shop's Telegram chat upon ShopOrderModel creation

feat: Create Celery task to send shop order invoice via Telegram

feat: Add invoice download endpoints for OrderModel and ShopOrderModel

feat: Implement views for downloading order and shop order invoices

chore: Update requirements.txt to include necessary packages for PDF generation

feat: Create HTML templates for order and shop order invoices

backend/order/signals.py

@@ -6,7 +6,8 @@ from django.dispatch import receiver
 from .models import OrderModel
 from account.models import PushSubscription, UserAddressModel
 import ghasedak_sms
-from .tasks import send_change_status_notif, send_change_status_sms
+from .tasks import send_change_status_notif, send_change_status_sms, send_shop_order_invoice_telegram_task
+from django.conf import settings
 
 
 @receiver(pre_save, sender=OrderModel)
@@ -180,3 +181,37 @@ def create_shop_orders_on_payment(sender, instance: OrderModel, created, **kwarg
                     special_discount_amount=int(
                         it.special_discount_amount or 0),
                 )
+
+
+@receiver(post_save, sender=ShopOrderModel)
+def send_invoice_to_shop_telegram(sender, instance: ShopOrderModel, created, **kwargs):
+    """Automatically send invoice to shop's Telegram chat when ShopOrderModel is created.
+    
+    This handler triggers when a new ShopOrderModel is created and the shop has a telegram_chat_id configured.
+    It sends the invoice PDF asynchronously via Celery task.
+    """
+    if not created:
+        return
+    
+    # Check if shop has telegram_chat_id configured
+    if not instance.shop or not instance.shop.telegram_chat_id:
+        return
+    
+    # Get bot token from settings
+    bot_token = getattr(settings, 'TELEGRAM_BOT_TOKEN', None)
+    if not bot_token:
+        return
+    
+    # Send invoice asynchronously
+    try:
+        send_shop_order_invoice_telegram_task.delay(
+            shop_order_id=instance.pk,
+            chat_id=instance.shop.telegram_chat_id,
+            bot_token=bot_token
+        )
+    except Exception as e:
+        send_shop_order_invoice_telegram_task(
+            shop_order_id=instance.pk,
+            chat_id=instance.shop.telegram_chat_id,
+            bot_token=bot_token
+        )