Fix Docker networking and add graceful MongoDB error handling

- Fix DNS resolution: Removed invalid dns_search configuration
- Add graceful MongoDB connection error handling
- Set restart policy to 'unless-stopped' for both services
- Add development helper scripts (start-dev.sh, stop-dev.sh)
- Update Docker Compose configurations for development
- Restore main.rs from git history
- Backend now logs MongoDB errors without crashing

All containers now start successfully with proper DNS resolution
on the dedicated normogen-network.

backend/start-dev.sh

@@ -0,0 +1,57 @@
+#!/bin/bash
+set -e
+
+echo "🚀 Starting Normogen Backend Development Environment..."
+cd "$(dirname "$0")"
+
+# Build and start containers
+echo "📦 Building and starting containers..."
+docker-compose -f docker-compose.dev.yml up --build -d
+
+# Wait for MongoDB to be healthy
+echo "⏳ Waiting for MongoDB to be healthy..."
+timeout=60
+while [ $timeout -gt 0 ]; do
+    if docker inspect normogen-mongodb-dev --format='{{.State.Health.Status}}' | grep -q "healthy"; then
+        echo "✅ MongoDB is healthy!"
+        break
+    fi
+    sleep 2
+    timeout=$((timeout - 2))
+done
+
+if [ $timeout -eq 0 ]; then
+    echo "❌ MongoDB health check timeout"
+    exit 1
+fi
+
+# Wait for backend to be ready
+echo "⏳ Waiting for backend to start..."
+timeout=30
+while [ $timeout -gt 0 ]; do
+    if curl -s http://localhost:6500/health > /dev/null 2>&1; then
+        echo "✅ Backend is ready!"
+        break
+    fi
+    sleep 2
+    timeout=$((timeout - 2))
+done
+
+if [ $timeout -eq 0 ]; then
+    echo "⚠️  Backend may still be starting..."
+fi
+
+echo ""
+echo "🎉 Development environment is ready!"
+echo ""
+echo "📊 Services:"
+docker-compose -f docker-compose.dev.yml ps
+echo ""
+echo "🔗 Backend: http://localhost:6500"
+echo "🔗 MongoDB: mongodb://localhost:27017"
+echo ""
+echo "📝 To view logs:"
+echo "   docker-compose -f docker-compose.dev.yml logs -f"
+echo ""
+echo "🛑 To stop:"
+echo "   ./stop-dev.sh"