fix: Resolve Docker permission issues in development environment

- Create dedicated Dockerfile.backend.dev for development with proper permissions
- Set user UID/GID to 1000 (common for development systems)
- Create logs and temp directories in Dockerfile before switching user
- Use named volumes for logs, temp, and node_modules to maintain permissions
- Mount only source files instead of entire backend directory
- Remove complex entrypoint script in favor of simple CMD
- Add LOG_DIR and TEMP_DIR environment variables

This fixes the "Permission denied" errors when creating directories in Docker.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

docker/Dockerfile.backend

@@ -21,14 +21,10 @@ COPY . .
 RUN addgroup -g 1001 -S nodejs && \
     adduser -S nodejs -u 1001
 
-# Create logs directory with proper permissions
-RUN mkdir -p logs && \
+# Create necessary directories with proper permissions
+RUN mkdir -p logs temp && \
     chown -R nodejs:nodejs /app && \
-    chmod 755 logs
-
-# Copy and set permissions for entrypoint
-COPY docker-entrypoint.sh /usr/local/bin/
-RUN chmod +x /usr/local/bin/docker-entrypoint.sh
+    chmod 755 logs temp
 
 # Switch to non-root user
 USER nodejs
@@ -37,4 +33,4 @@ USER nodejs
 EXPOSE 3000
 
 # Start the application
-ENTRYPOINT ["docker-entrypoint.sh"]
+CMD ["node", "src/app.js"]