feat(website): 三轮视觉改造与页面过渡动画

改造概要（30项）：
- 第一轮：Hero重构/Section差异化/SocialProof强化/CTA对比度/About架构
- 第二轮：字体优化/背景交替/Solutions差异化/Footer五列/MegaDropdown修复
- 第三轮：卡片交互/表单层级/CTA统一/时间线标记/连接线/三列布局/移动导航/Button微交互/SEO Schema
- P3-2：template.tsx+Framer Motion页面过渡/loading.tsx加载状态
- 清理：删除未用组件/hooks，修复重复移动导航，清理冗余CSS

src/components/ui/textarea.tsx

@@ -18,10 +18,10 @@ const Textarea = React.forwardRef<HTMLTextAreaElement, TextareaProps>(
         {label && (
           <label
             htmlFor={textareaId}
-            className="block text-sm font-medium text-[#3D3D3D] mb-2"
+            className="block text-sm font-medium text-[var(--color-text-secondary)] mb-2"
           >
             {label}
-            {props.required && <span className="text-[#C41E3A] ml-1">*</span>}
+            {props.required && <span className="text-[var(--color-brand-primary)] ml-1">*</span>}
           </label>
         )}
         <textarea
@@ -29,10 +29,10 @@ const Textarea = React.forwardRef<HTMLTextAreaElement, TextareaProps>(
           data-slot="textarea"
           data-testid={props['data-testid']}
           className={cn(
-            "placeholder:text-[#8C8C8C] selection:bg-[#1C1C1C] selection:text-white min-h-[140px] w-full rounded-lg border border-[#E5E5E5] bg-[#FAFAFA] px-4 py-3 text-base text-[#1C1C1C] shadow-sm transition-all duration-300 outline-none disabled:cursor-not-allowed disabled:opacity-50 md:min-h-[80px] md:text-sm md:py-2 resize-none",
-            "focus-visible:border-[#1C1C1C] focus-visible:ring-2 focus-visible:ring-[#1C1C1C]/50 focus-visible:shadow-lg focus-visible:shadow-[#1C1C1C]/20",
-            "hover:border-[#3D3D3D]",
-            error && "border-[#C41E3A] focus-visible:border-[#C41E3A] focus-visible:ring-[#C41E3A]/50",
+            "placeholder:text-[var(--color-text-hint)] selection:bg-[var(--color-primary)] selection:text-white min-h-[140px] w-full rounded-lg border border-[var(--color-border-primary)] bg-[var(--color-bg-section)] px-4 py-3 text-base text-[var(--color-text-primary)] shadow-sm transition-all duration-300 outline-none disabled:cursor-not-allowed disabled:opacity-50 md:min-h-[80px] md:text-sm md:py-2 resize-none",
+            "focus-visible:border-[var(--color-primary)] focus-visible:ring-2 focus-visible:ring-[var(--color-primary)]/50 focus-visible:shadow-lg focus-visible:shadow-[var(--color-primary)]/20",
+            "hover:border-[var(--color-text-secondary)]",
+            error && "border-[var(--color-brand-primary)] focus-visible:border-[var(--color-brand-primary)] focus-visible:ring-[var(--color-brand-primary)]/50",
             className
           )}
           ref={ref}
@@ -42,7 +42,7 @@ const Textarea = React.forwardRef<HTMLTextAreaElement, TextareaProps>(
           {...props}
         />
         {error && (
-          <p id={errorId} className="mt-1 text-sm text-[#C41E3A]" role="alert">
+          <p id={errorId} className="mt-1 text-sm text-[var(--color-brand-primary)]" role="alert">
             {error}
           </p>
         )}