ui: 全站统一暗色主题设计系统

- globals.css 定义语义化 token (background/surface/elevated/border/muted/dim/accent)
- 所有页面和组件迁移至暗色 token，移除硬编码 bg-white/text-zinc-*/bg-gray-*
- RestaurantCard 和 MatchResult 适配暗色卡片风格
- 按钮颜色分层：系统CTA(accent)/模式强调(橙/紫)/危险(rose)/次级(surface)
- 修复 room 页深色文字在深背景不可见的可访问性问题

src/components/QrInviteModal.tsx

@@ -66,7 +66,7 @@ export default function QrInviteModal({
       {open && (
         <motion.div
           ref={backdropRef}
-          className="fixed inset-0 z-50 flex items-end justify-center bg-black/40 backdrop-blur-sm sm:items-center"
+          className="fixed inset-0 z-50 flex items-end justify-center bg-black/60 backdrop-blur-sm sm:items-center"
           initial={{ opacity: 0 }}
           animate={{ opacity: 1 }}
           exit={{ opacity: 0 }}
@@ -74,7 +74,7 @@ export default function QrInviteModal({
           onClick={handleBackdropClick}
         >
           <motion.div
-            className="relative w-full max-w-sm rounded-t-3xl bg-white px-6 pb-8 pt-5 shadow-2xl sm:rounded-3xl sm:pb-6"
+            className="relative w-full max-w-sm rounded-t-3xl bg-surface px-6 pb-8 pt-5 shadow-2xl ring-1 ring-border sm:rounded-3xl sm:pb-6"
             initial={{ y: "100%" }}
             animate={{ y: 0 }}
             exit={{ y: "100%" }}
@@ -82,33 +82,33 @@ export default function QrInviteModal({
           >
             <button
               onClick={onClose}
-              className="absolute right-4 top-4 flex h-8 w-8 items-center justify-center rounded-full bg-zinc-100 text-zinc-400 transition-colors active:bg-zinc-200"
+              className="absolute right-4 top-4 flex h-8 w-8 items-center justify-center rounded-full bg-elevated text-muted transition-colors active:bg-subtle"
             >
               <X size={16} />
             </button>
 
             <div className="flex flex-col items-center">
-              <div className="flex items-center gap-2 text-zinc-800">
-                <QrCode size={18} className="text-emerald-500" />
+              <div className="flex items-center gap-2 text-white">
+                <QrCode size={18} className="text-accent" />
                 <h2 className="text-lg font-bold">邀请饭搭子</h2>
               </div>
-              <p className="mt-1 text-xs text-zinc-400">
+              <p className="mt-1 text-xs text-muted">
                 {sceneConfig.qrSubtitle}
               </p>
 
-              <div className="mt-5 rounded-2xl border-2 border-dashed border-emerald-200 bg-emerald-50/30 p-4">
+              <div className="mt-5 rounded-2xl border-2 border-dashed border-subtle bg-elevated/50 p-4">
                 <QRCodeSVG
                   value={inviteUrl}
                   size={180}
                   level="M"
                   bgColor="transparent"
-                  fgColor="#18181b"
+                  fgColor="#e5e7eb"
                 />
               </div>
 
               <div className="mt-4 flex items-center gap-2">
-                <span className="text-xs text-zinc-400">房间号</span>
-                <span className="rounded-full bg-zinc-100 px-3 py-1 font-mono text-base font-bold tracking-[0.2em] text-emerald-600">
+                <span className="text-xs text-muted">房间号</span>
+                <span className="rounded-full bg-elevated px-3 py-1 font-mono text-base font-bold tracking-[0.2em] text-accent ring-1 ring-border">
                   {roomId}
                 </span>
               </div>
@@ -116,14 +116,14 @@ export default function QrInviteModal({
               <div className="mt-5 flex w-full gap-2.5">
                 <button
                   onClick={handleCopy}
-                  className="flex h-11 flex-1 items-center justify-center gap-1.5 rounded-xl border border-zinc-200 bg-white text-sm font-semibold text-zinc-700 transition-colors active:bg-zinc-50"
+                  className="flex h-11 flex-1 items-center justify-center gap-1.5 rounded-xl bg-elevated text-sm font-semibold text-gray-300 ring-1 ring-border transition-colors active:bg-subtle"
                 >
                   <Copy size={15} />
                   复制链接
                 </button>
                 <button
                   onClick={handleShare}
-                  className="flex h-11 flex-1 items-center justify-center gap-1.5 rounded-xl bg-emerald-500 text-sm font-semibold text-white shadow-md shadow-emerald-200 transition-colors active:bg-emerald-600"
+                  className="flex h-11 flex-1 items-center justify-center gap-1.5 rounded-xl bg-accent text-sm font-semibold text-white shadow-lg shadow-accent/20 transition-colors active:bg-accent-hover"
                 >
                   <Share2 size={15} />
                   发送邀请