refactor: optimize system health monitoring and UI interactions

- Removed unnecessary delay in chat redirection for immediate user feedback.
- Enhanced TitleBar component with a system health indicator, displaying RAM and CPU usage.
- Implemented optimistic UI updates for model downloads and Ollama installation, improving responsiveness.
- Introduced background health monitoring to prevent resource overload during operations.
- Added cleanup logic for child processes to ensure proper resource management during application shutdown.

hooks/use-system-health.ts

@@ -0,0 +1,53 @@
+'use client';
+
+import { useEffect, useState } from 'react';
+import { listen } from '@tauri-apps/api/event';
+import { useToast } from '@/hooks/use-toast';
+
+export type HealthStatus = 'healthy' | 'warning' | 'critical';
+
+export interface SystemHealth {
+  status: HealthStatus;
+  ram_percent: number;
+  cpu_percent: number;
+  message: string;
+}
+
+export function useSystemHealth() {
+  const [health, setHealth] = useState<SystemHealth>({
+    status: 'healthy',
+    ram_percent: 0,
+    cpu_percent: 0,
+    message: 'Sistema saudável',
+  });
+  const [hasShownCriticalToast, setHasShownCriticalToast] = useState(false);
+  const { toast } = useToast();
+
+  useEffect(() => {
+    const unlistenPromise = listen<SystemHealth>('system-state-change', (event) => {
+      const newHealth = event.payload;
+      setHealth(newHealth);
+
+      // Mostrar toast apenas quando entrar em modo Critical (uma vez)
+      if (newHealth.status === 'critical' && !hasShownCriticalToast) {
+        toast({
+          title: 'Modo de Economia Ativado',
+          description: 'Recursos limitados para manter estabilidade. Algumas funcionalidades podem estar temporariamente indisponíveis.',
+          variant: 'destructive',
+          duration: 5000,
+        });
+        setHasShownCriticalToast(true);
+      } else if (newHealth.status !== 'critical') {
+        // Reset flag quando sair do modo crítico
+        setHasShownCriticalToast(false);
+      }
+    });
+
+    return () => {
+      unlistenPromise.then((unlisten) => unlisten());
+    };
+  }, [hasShownCriticalToast, toast]);
+
+  return health;
+}
+