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/Dockerfile

@@ -2,7 +2,13 @@ FROM python:3.12-slim
 
 WORKDIR /app
 
-RUN apt update && apt install ffmpeg -y
+RUN apt update && apt install -y \
+    weasyprint \
+    libcairo2 \
+    pango1.0-tools \
+    libpango-1.0-0 \
+    libgobject-2.0-0 \
+    ffmpeg
 
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt