Major refactor of commerce and Stripe integration

Refactored commerce models to support refunds, invoices, and improved carrier/payment logic. Added new serializers and viewsets for products, categories, images, discount codes, and refunds. Introduced Stripe client integration and removed legacy Stripe admin/model code. Updated Dockerfile for PDF generation dependencies. Removed obsolete migration files and updated configuration app initialization. Added invoice template and tasks for order cleanup.

backend/thirdparty/stripe/client.py

@@ -0,0 +1,54 @@
+import stripe
+from django.conf import settings
+import json
+import os
+
+FRONTEND_URL = os.getenv("FRONTEND_URL") if not settings.DEBUG else os.getenv("DEBUG_DOMAIN")
+SSL = "https://" if os.getenv("USE_SSL") == "true" else "http://"
+
+stripe.api_key = os.getenv("STRIPE_SECRET_KEY")
+
+class StripeClient:
+
+    def create_checkout_session(order):
+        """
+        Vytvoří Stripe Checkout Session pro danou objednávku.
+        Args:
+            order (Order): Instance objednávky pro kterou se vytváří session.
+        
+        Returns:
+            stripe.checkout.Session: Vytvořená Stripe Checkout Session.
+        """
+
+        session = stripe.checkout.Session.create(
+            mode="payment",
+            payment_method_types=["card"],
+
+            success_url=f"{SSL}{FRONTEND_URL}/payment/success?order={order.id}", #jenom na grafickou část (webhook reálně ověří stav)
+            cancel_url=f"{SSL}{FRONTEND_URL}/payment/cancel?order={order.id}",
+
+            client_reference_id=str(order.id),
+            line_items=[{
+                "price_data": {
+                    "currency": "czk",
+                    "product_data": {
+                        "name": f"Objednávka {order.id}",
+                    },
+                    "unit_amount": int(order.total_price * 100),  # cena v haléřích
+                },
+                "quantity": 1,
+            }],
+        )
+
+        return session
+
+
+    def refund_order(stripe_payment_intent):
+        try:
+            refund = stripe.Refund.create(
+                payment_intent=stripe_payment_intent
+            )
+            return refund
+        
+        except Exception as e:
+            return json.dumps({"error": str(e)})