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.dev

@@ -0,0 +1,41 @@
+FROM node:20-alpine
+
+# Install MinIO client
+RUN wget https://dl.min.io/client/mc/release/linux-amd64/mc && \
+    chmod +x mc && \
+    mv mc /usr/local/bin/
+
+# Install development dependencies
+RUN apk add --no-cache bash
+
+# Create app directory
+WORKDIR /app
+
+# Create non-root user (same UID/GID as most development systems)
+RUN addgroup -g 1000 -S nodejs && \
+    adduser -S nodejs -u 1000 -G nodejs
+
+# Copy package files
+COPY package*.json ./
+
+# Install dependencies as root
+RUN npm install
+
+# Create necessary directories
+RUN mkdir -p logs temp && \
+    chmod 755 logs temp
+
+# Copy application files
+COPY . .
+
+# Change ownership of everything to nodejs user
+RUN chown -R nodejs:nodejs /app
+
+# Switch to non-root user
+USER nodejs
+
+# Expose port
+EXPOSE 7510
+
+# Start the application in development mode
+CMD ["npm", "run", "dev"]