fix: configure CI database connection properly

- Add dotenv loading to Django settings
- Update CI workflow to use correct environment variables
- Set POSTGRES_* variables instead of DATABASE_URL
- Add environment variables to all Django management commands
- Fixes CI test failures due to database connection issues

app/Dockerfile

@@ -4,7 +4,8 @@ ENV PYTHONDONTWRITEBYTECODE=1 \
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     build-essential libpq-dev postgresql-client \
-    libpango-1.0-0 libcairo2 libffi-dev \
+    libpango-1.0-0 libpangoft2-1.0-0 libcairo2 libffi-dev \
+    libgdk-pixbuf-xlib-2.0-0 libharfbuzz0b libfribidi0 \
     libjpeg-dev libpng-dev \
     && rm -rf /var/lib/apt/lists/*