Fix file permissions for data directory in Docker

Dockerfile

@@ -23,8 +23,8 @@ RUN npm run build
 # Production stage
 FROM node:20-alpine AS runner
 
-# Install Python and yt-dlp dependencies
-RUN apk add --no-cache python3 py3-pip ffmpeg
+# Install Python, yt-dlp dependencies, and su-exec
+RUN apk add --no-cache python3 py3-pip ffmpeg su-exec
 
 # Install yt-dlp
 RUN pip3 install --no-cache-dir yt-dlp --break-system-packages
@@ -45,11 +45,19 @@ COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static
 # Create data directory for database
 RUN mkdir -p /app/data && chown -R nextjs:nodejs /app
 
-USER nextjs
+# Switch to root to allow permission fixes on startup
+USER root
 
 EXPOSE 3000
 
-ENV PORT 3000
-ENV HOSTNAME "0.0.0.0"
+ENV PORT=3000
+ENV HOSTNAME="0.0.0.0"
 
-CMD ["node", "server.js"]
+# Create startup script that fixes permissions and starts the app
+RUN echo '#!/bin/sh' > /start.sh && \
+    echo 'mkdir -p /app/data' >> /start.sh && \
+    echo 'chown -R nextjs:nodejs /app/data' >> /start.sh && \
+    echo 'su-exec nextjs node server.js' >> /start.sh && \
+    chmod +x /start.sh
+
+CMD ["/start.sh"]