feat: 深度设计五站视觉语言 + 语言路由修复

- 语言路由：localeDetection 关闭，/ 固定英文、/zh 固定中文，URL 决定语言
  （不再按 cookie/Accept-Language 自动跳转；语言切换器显式切换不受影响）
- 五站独立视觉语言（data-theme 驱动的设计系统层）：
  · AI Stack：深蓝渐变 Hero + 统计条 + 卡片左色条 hover（专业 SaaS）
  · LaunchAI：橙色渐变 Banner + 斜切底边 + 暖白底（活力社区）
  · The AI Ledger：黑色报头日期条 + 衬线字体 + 直角 + 双细线 + 报纸排版（媒体）
  · DevAI.tools：全站深色 + 等宽字体 + 终端 Hero + 扫描线纹理 + 系统状态条（终端）
  · findai：纯白极简 + 紫色聚焦光圈 + 无界卡片（搜索引擎）
- 修复 :first-of-type 误伤（hero 样式收敛到专用 class）

sites/ai-stack/src/site/brand.tsx

@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // AI Stack —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeClass": "site-ai-stack",
   "brandZh": {
     "name": "AI Stack",
     "tagline": "由真实用户排名的专业 AI 工具目录。",

sites/ai-stack/src/site/home.tsx

@@ -58,7 +58,7 @@ async function SiteHome({ locale }: { locale: string }) {
   return (
     <div className="bg-background">
       {/* Hero */}
-      <section className="border-b border-border bg-gradient-to-b from-secondary/40 to-background">
+      <section className="hero-dark border-b border-border">
         <div className="mx-auto max-w-7xl px-4 py-16 text-center sm:px-6 md:py-24">
           <h1 className="mx-auto max-w-3xl text-3xl font-bold tracking-tight text-foreground sm:text-4xl md:text-5xl">
             {th("title")}
@@ -83,13 +83,28 @@ async function SiteHome({ locale }: { locale: string }) {
               </button>
             </div>
           </form>
-          <div className="mt-4 flex flex-wrap items-center justify-center gap-2 text-xs text-muted-foreground">
-            <span>{t("popularLabel")}</span>
+
+          {/* 统计条（深色 Hero 内的白色数字） */}
+          <div className="mx-auto mt-10 flex max-w-lg items-center justify-center gap-10 border-t border-white/15 pt-6">
+            {[
+              { v: "1,000+", l: "AI tools" },
+              { v: "14", l: "Categories" },
+              { v: "7", l: "Rankings" },
+            ].map((s) => (
+              <div key={s.l} className="text-center">
+                <div className="text-2xl font-bold text-white">{s.v}</div>
+                <div className="text-xs text-white/60">{s.l}</div>
+              </div>
+            ))}
+          </div>
+
+          <div className="mt-8 flex flex-wrap items-center justify-center gap-2 text-xs">
+            <span className="text-white/60">{t("popularLabel")}</span>
             {t.raw("popularSearches").map((q: string) => (
               <LocaleLink
                 key={q}
                 href={`/tools?search=${q}`}
-                className="rounded-full bg-secondary px-2.5 py-1 transition-colors hover:bg-hover"
+                className="rounded-full bg-white/10 px-2.5 py-1 text-white/80 transition-colors hover:bg-white/20"
               >
                 {q}
               </LocaleLink>

sites/devai-tools/src/site/brand.tsx

@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // DevAI.tools —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeClass": "site-devai-tools",
   "brandZh": {
     "name": "DevAI.tools",
     "tagline": "面向开发者的 AI 工具——精选、实测、社区排名。",

sites/devai-tools/src/site/home.tsx

@@ -51,7 +51,13 @@ async function SiteHome({ locale }: { locale: string }) {
 
   return (
     <div className="min-h-screen bg-background">
-      {/* Terminal 风格 Hero */}
+      {/* Terminal 风格 Hero + 绿色系统状态条 */}
+      <div className="border-b border-border bg-background">
+        <div className="mx-auto flex max-w-5xl items-center gap-2 px-4 py-2 font-mono text-[11px] text-muted-foreground sm:px-6">
+          <span className="inline-block h-2 w-2 animate-pulse rounded-full bg-emerald-500" />
+          system: online · 1,000+ tools indexed · updated hourly
+        </div>
+      </div>
       <section className="border-b border-border bg-[hsl(var(--secondary))]/40">
         <div className="mx-auto max-w-5xl px-4 py-14 sm:px-6 md:py-20">
           <div className="mx-auto max-w-2xl overflow-hidden rounded-xl border border-border bg-background shadow-sm">

sites/findai/src/site/brand.tsx

@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // findai —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeClass": "site-findai",
   "brandZh": {
     "name": "findai",
     "tagline": "极简 AI 工具搜索引擎。",

sites/findai/src/site/home.tsx

@@ -73,6 +73,7 @@ async function SiteHome({ locale }: { locale: string }) {
           </div>
         </form>
 
+        <div className="mx-auto mt-10 max-w-md border-t border-border/60 pt-5" />
         <div className="mt-6 flex flex-wrap items-center justify-center gap-2">
           {popularSearches.map((q) => (
             <LocaleLink

sites/launchai/src/site/brand.tsx

@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // LaunchAI —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeClass": "site-launchai",
   "brandZh": {
     "name": "LaunchAI",
     "tagline": "发现并投票今日的 AI 新品。",

sites/launchai/src/site/home.tsx

@@ -111,7 +111,7 @@ async function SiteHome({ locale }: { locale: string }) {
   return (
     <div className="min-h-screen bg-background">
       {/* Hero：今日发布 */}
-      <section className="border-b border-border bg-gradient-to-b from-primary/5 to-background">
+      <section className="hero-launch border-b border-border bg-gradient-to-b from-primary/5 to-background">
         <div className="mx-auto max-w-5xl px-4 py-12 text-center sm:px-6 md:py-16">
           <h1 className="text-2xl font-extrabold tracking-tight text-foreground sm:text-4xl">
             {th("title")}

sites/the-ai-ledger/src/site/brand.tsx

@@ -2,6 +2,7 @@ import type { SiteConfig } from "@/kit/types";
 
 // The AI Ledger —— 独立站点的全部品牌/导航/页脚配置
 export const siteConfig: SiteConfig = {
+  "themeClass": "site-the-ai-ledger",
   "brandZh": {
     "name": "The AI Ledger",
     "tagline": "独立 AI 报道，附社区排名目录。",

sites/the-ai-ledger/src/site/home.tsx

@@ -54,6 +54,15 @@ async function SiteHome({ locale }: { locale: string }) {
 
   return (
     <div className="min-h-screen bg-background">
+      {/* Masthead：黑色报头条（当日日期 + 期号），报纸头版签名 */}
+      <div className="bg-foreground text-background">
+        <div className="mx-auto flex max-w-4xl items-center justify-between px-4 py-2 text-[11px] uppercase tracking-[0.25em] sm:px-6">
+          <span>{new Date().toLocaleDateString("en-US", { weekday: "long", year: "numeric", month: "long", day: "numeric" })}</span>
+          <span className="hidden sm:inline">Est. 2026</span>
+          <span>Daily</span>
+        </div>
+      </div>
+
       {/* Masthead */}
       <section className="border-b border-border">
         <div className="mx-auto max-w-4xl px-4 py-16 text-center sm:px-6 md:py-20">