fix: Resolve Coolify build failure by fixing requirements.txt PyPI versions, adding gunicorn, and using standard pip in Dockerfile

backend/Dockerfile

@@ -2,19 +2,19 @@ FROM python:3.11-slim
 
 WORKDIR /app
 
-# Install system dependencies
+# Install system dependencies needed for compiling C extensions (psycopg2, pillow, reportlab)
 RUN apt-get update && apt-get install -y --no-install-recommends \
     gcc \
     libpq-dev \
+    libjpeg-dev \
+    zlib1g-dev \
     curl \
     && rm -rf /var/lib/apt/lists/*
 
-# Install uv for fast dependency management
-COPY --from=ghcr.io/astral-sh/uv:latest /uv /bin/uv
-
-# Copy requirements and install via uv
+# Copy requirements and install
 COPY requirements.txt .
-RUN uv pip install --system -r requirements.txt
+RUN pip install --no-cache-dir --upgrade pip && \
+    pip install --no-cache-dir -r requirements.txt
 
 # Copy backend application code
 COPY . .