fix(theme): 品牌色令牌语义拆分与暗黑模式全站治理

- 拆分品牌色「文字/底色」双通道：新增 --color-brand-ink(-rgb)（深色 #F87171）
  与 tailwind brand.ink；text-brand → text-brand-ink 迁移 247 处；
  bg-brand/border-brand 保持 --color-brand-rgb 不翻转（红底白字 5.58:1 不能动）
- dark 块补齐 --color-brand-bg: #2A1418（修复深色白字压浅粉底 1.04:1）
- hero 徽章新增 --badge-accent-text 桥接：accentColor 直用作深底文字不可读
  （#1e3a5f 深底 1.65:1），浅色取原色 / 深色 color-mix 提亮
- 硬编码颜色 token 化：bg-white/text-gray-*/border-gray-* → bg-bg-*/text-text-*/border-border-*
- 可访问性：触控目标 <24px 归零（footer 链接列 [&_a]:min-h-6 收口 377 处等）、
  news 搜索框补 aria-label、标题跳级 h2→h4 修正为 h3、装饰 blur 光斑容器补
  overflow-hidden 消除伪文本裁剪
- 验证：tsc 0 / eslint 0 error / jest 0 失败用例 / dogfood 33 路由 × 双主题 P1-P3 全零

src/app/(marketing)/solutions/solutions-content-v3.tsx

@@ -41,7 +41,7 @@ function HeroSection({ pageCopy }: { pageCopy?: PageCopy | null }) {
             <div className="block">{heroTitle1}</div>
             <div className="block mt-4 sm:mt-6">
               <span className="relative inline-block">
-                <span className="relative text-brand font-black">
+                <span className="relative text-brand-ink font-black">
                   {heroTitle2}
                   <motion.span
                     className="absolute -bottom-2 left-0 w-full h-[3px] bg-brand"
@@ -91,19 +91,19 @@ function HeroSection({ pageCopy }: { pageCopy?: PageCopy | null }) {
           >
             <div>
               <div className="text-3xl sm:text-4xl font-black text-ink tracking-tight leading-none mb-2">
-                6<span className="text-brand">大</span>
+                6<span className="text-brand-ink">大</span>
               </div>
               <div className="text-sm text-text-muted">行业覆盖</div>
             </div>
             <div>
               <div className="text-3xl sm:text-4xl font-black text-ink tracking-tight leading-none mb-2">
-                端到<span className="text-brand">端</span>
+                端到<span className="text-brand-ink">端</span>
               </div>
               <div className="text-sm text-text-muted">交付模式</div>
             </div>
             <div>
               <div className="text-3xl sm:text-4xl font-black text-ink tracking-tight leading-none mb-2">
-                定制<span className="text-brand">化</span>
+                定制<span className="text-brand-ink">化</span>
               </div>
               <div className="text-sm text-text-muted">方案特点</div>
             </div>
@@ -153,7 +153,7 @@ function SolutionCard({ solution, index, products, featured = false }: { solutio
           <div className="grid grid-cols-2 gap-2 mb-4">
             {solution.outcomes?.map((o) => (
               <div key={o.label} className="p-2 bg-bg-secondary">
-                <div className="text-base font-bold text-brand">{o.value}</div>
+                <div className="text-base font-bold text-brand-ink">{o.value}</div>
                 <div className="text-xs text-text-muted">{o.label}</div>
               </div>
             ))}
@@ -170,7 +170,7 @@ function SolutionCard({ solution, index, products, featured = false }: { solutio
             </div>
           </div>
 
-          <div className="inline-flex items-center gap-2 text-sm font-semibold text-text-secondary group-hover:text-brand transition-colors duration-300 mt-6">
+          <div className="inline-flex items-center gap-2 text-sm font-semibold text-text-secondary group-hover:text-brand-ink transition-colors duration-300 mt-6">
             <span>了解详情</span>
             <ArrowUpRight className="w-4 h-4 group-hover:translate-x-0.5 group-hover:-translate-y-0.5 transition-transform duration-300" />
           </div>