fix: Forward real client IP through Docker proxy

- Update setupProxy.js to forward X-Real-IP and X-Forwarded-For headers
- Improve IP detection in backend middleware to prioritize X-Real-IP
- Add debug logging for IP detection in development mode
- Update .env.example with clearer IP configuration examples
- Enable debug logging in docker-compose.dev.yml

This fixes the issue where Docker network IPs (172.20.x.x) were being
detected instead of the real client IP addresses.

To fix IP restrictions, update your .env file:
ALLOWED_IPS=10.30.30.0/24,<your-other-ips>

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

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

.env.example

@@ -10,7 +10,11 @@ SESSION_TIMEOUT=1800
 
 # IP Restrictions
 ENABLE_IP_RESTRICTION=true
-ALLOWED_IPS=192.168.1.0/24,10.0.0.5,172.16.0.0/16
+# Add your IP or subnet here. Examples:
+# - Single IP: 10.30.30.2
+# - Subnet: 10.30.30.0/24
+# - Multiple: 10.30.30.2,192.168.1.0/24,172.16.0.0/16
+ALLOWED_IPS=10.30.30.0/24,192.168.1.0/24,172.16.0.0/16,127.0.0.1
 
 # MinIO Configuration
 DEFAULT_MINIO_ALIAS=kopiaminio