Fix Dockerfile: Switch from Alpine to Debian Slim for better Python package compatibility

Changes:
- Use python:3.11-slim instead of python:3.11-alpine
- Install libgl1-mesa-glx and libglib2.0-0 for rembg dependencies
- Remove gcc and musl-dev (not needed in Debian)
- Fixes build errors with opencv-python-headless, numba, and llvmlite
- Debian provides better support for Python packages with C extensions

Dockerfile

@@ -1,11 +1,15 @@
-FROM python:3.11-alpine
+FROM python:3.11-slim
 
 # Set environment variables
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONUNBUFFERED=1
 
 # Install system dependencies
-RUN apk add --no-cache gcc musl-dev ffmpeg
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    ffmpeg \
+    libgl1-mesa-glx \
+    libglib2.0-0 \
+    && rm -rf /var/lib/apt/lists/*
 
 # Set work directory
 WORKDIR /app
@@ -20,7 +24,7 @@ RUN pip install --no-cache-dir -r requirements.txt
 COPY . .
 
 # Create non-root user
-RUN adduser -D -u 1000 appuser && chown -R appuser:appuser /app
+RUN adduser --disabled-password --gecos '' --uid 1000 appuser && chown -R appuser:appuser /app
 USER appuser
 
 # Health check