feat: 添加预览效果页面并优化交互效果

refactor: 优化代码健壮性和类型安全

style: 更新字体样式和全局CSS

fix: 修复IntersectionObserver潜在空引用问题

chore: 更新依赖和ESLint配置

build: 更新构建ID和路由配置

src/app/(marketing)/about/page.tsx

@@ -134,7 +134,7 @@ export default function AboutPage() {
                     <div className="font-semibold text-black text-sm md:text-base">{milestone.date}</div>
                   </div>
                   <div className="flex-1 pb-6 border-l-2 border-gray-200 pl-6 relative">
-                    <div className="absolute -left-[9px] top-1 w-4 h-4 bg-black rounded-full"></div>
+                    <div className="absolute -left-[9px] top-1 w-4 h-4 bg-black rounded-full" />
                     <h3 className="font-semibold text-black mb-1">{milestone.title}</h3>
                     <p className="text-gray-600 text-sm leading-relaxed">{milestone.description}</p>
                   </div>

src/app/(marketing)/cases/[id]/client.tsx

@@ -1,12 +1,11 @@
 'use client';
 
 import { useEffect, useRef, useState } from 'react';
-import Image from 'next/image';
 import Link from 'next/link';
 import { Button } from '@/components/ui/button';
 import { Badge } from '@/components/ui/badge';
 import { ArrowLeft, Building2, CheckCircle2, TrendingUp, Users, Target } from 'lucide-react';
-import { CASES, COMPANY_INFO } from '@/lib/constants';
+import { CASES } from '@/lib/constants';
 import type { StaticImageData } from 'next/image';
 
 interface CaseResult {
@@ -36,7 +35,7 @@ export function CaseDetailClient({ caseItem }: CaseDetailClientProps) {
   useEffect(() => {
     const observer = new IntersectionObserver(
       ([entry]) => {
-        if (entry.isIntersecting) {
+        if (entry?.isIntersecting) {
           setIsVisible(true);
         }
       },
@@ -116,7 +115,7 @@ export function CaseDetailClient({ caseItem }: CaseDetailClientProps) {
               <section>
                 <h2 className="text-2xl font-semibold text-[#171717] mb-4">解决方案</h2>
                 <div className="space-y-4">
-                  {caseItem.tags.map((tag, index) => (
+                  {caseItem.tags.map((tag) => (
                     <div key={tag} className="flex items-start gap-3">
                       <div className="w-6 h-6 bg-[#C41E3A] rounded-full flex items-center justify-center flex-shrink-0 mt-0.5">
                         <CheckCircle2 className="w-4 h-4 text-white" />

src/app/(marketing)/contact/page.tsx

@@ -13,10 +13,9 @@ export default function ContactPage() {
   const [isSubmitting, setIsSubmitting] = useState(false);
   const [isSubmitted, setIsSubmitted] = useState(false);
 
-  async function handleSubmit(formData: FormData) {
+  async function handleSubmit(_formData: FormData) {
     setIsSubmitting(true);
     
-    // Simulate form submission
     await new Promise(resolve => setTimeout(resolve, 1500));
     
     setIsSubmitting(false);