feat(perf,ux): implement performance and UX optimizations

Phase 2: Performance Optimizations
- Implement dynamic imports for non-critical sections
- Add loading skeletons for lazy-loaded components
- Optimize bundle size with code splitting
- Enable SSR for dynamic components

Phase 3: UX Optimizations
- Create ErrorBoundary component for graceful error handling
- Add Toast notification component for user feedback
- Implement success/error notifications in contact form
- Add error handling with user-friendly messages

Files modified:
- src/app/(marketing)/page.tsx: Dynamic imports for sections
- src/app/(marketing)/layout.tsx: Error boundary integration
- src/components/sections/contact-section.tsx: Toast notifications
- src/components/ui/error-boundary.tsx: New error boundary component
- src/components/ui/toast.tsx: New toast notification component

Impact:
- Reduced initial bundle size
- Faster page load times
- Better error handling
- Improved user feedback
- Enhanced user experience

src/components/sections/contact-section.tsx

@@ -5,6 +5,7 @@ import { z } from 'zod';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Textarea } from '@/components/ui/textarea';
+import { Toast } from '@/components/ui/toast';
 import { Mail, Phone, MapPin, Send, Loader2, Clock, HeadphonesIcon, CheckCircle2 } from 'lucide-react';
 import { COMPANY_INFO } from '@/lib/constants';
 
@@ -28,6 +29,9 @@ export function ContactSection() {
   const [isVisible, setIsVisible] = useState(false);
   const [isSubmitting, setIsSubmitting] = useState(false);
   const [isSubmitted, setIsSubmitted] = useState(false);
+  const [showToast, setShowToast] = useState(false);
+  const [toastMessage, setToastMessage] = useState('');
+  const [toastType, setToastType] = useState<'success' | 'error'>('success');
   const [formData, setFormData] = useState<ContactFormData>({
     name: '',
     phone: '',
@@ -96,14 +100,31 @@ export function ContactSection() {
 
     setIsSubmitting(true);
     
-    await new Promise(resolve => setTimeout(resolve, 1500));
-    
-    setIsSubmitting(false);
-    setIsSubmitted(true);
+    try {
+      await new Promise(resolve => setTimeout(resolve, 1500));
+      
+      setIsSubmitting(false);
+      setIsSubmitted(true);
+      setToastMessage('表单提交成功！我们会尽快与您联系。');
+      setToastType('success');
+      setShowToast(true);
+    } catch (error) {
+      setIsSubmitting(false);
+      setToastMessage('提交失败，请稍后重试。');
+      setToastType('error');
+      setShowToast(true);
+    }
   }
 
   return (
     <section id="contact" className="section-padding relative bg-white overflow-hidden" ref={sectionRef}>
+      {showToast && (
+        <Toast
+          message={toastMessage}
+          type={toastType}
+          onClose={() => setShowToast(false)}
+        />
+      )}
       <div className="absolute inset-0 pointer-events-none">
         <div className="absolute inset-0 bg-gradient-radial from-[rgba(79,70,229,0.03)] via-transparent to-transparent" />
       </div>