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>

frontend/src/setupProxy.js

@@ -7,6 +7,20 @@ module.exports = function(app) {
       target: process.env.BACKEND_URL || 'http://backend:7510',
       changeOrigin: true,
       logLevel: 'debug',
+      // Forward the real IP address
+      onProxyReq: (proxyReq, req, res) => {
+        // Get the real client IP
+        const clientIp = req.headers['x-forwarded-for'] || 
+                        req.connection.remoteAddress ||
+                        req.socket.remoteAddress ||
+                        req.connection.socket.remoteAddress;
+        
+        // Set the forwarded headers
+        proxyReq.setHeader('X-Forwarded-For', clientIp);
+        proxyReq.setHeader('X-Real-IP', clientIp);
+        proxyReq.setHeader('X-Forwarded-Proto', req.protocol);
+        proxyReq.setHeader('X-Forwarded-Host', req.headers.host);
+      },
       onError: (err, req, res) => {
         console.error('Proxy Error:', err);
         res.status(500).json({ error: 'Proxy Error', message: err.message });