UI 全面重设计: 明亮画廊风格 + 剧集合并显示

## 色彩体系重构
- tailwind.config.js: sand/ink 全新色阶 + shadow 阴影预设
- index.css: 全组件系统重写 (card/input/btn/badge/table)

## 核心页面重写
- LoginPage: 纯白卡片 + 品牌光晕 + Framer Motion 入场动画
- HomePage: Billboard 推荐位 + 剧集卡片联动媒体库
- Layout: 白色侧边栏 + 路由过渡动画
- MediaCard: 新增 linkTo prop, 悬停浮层优化

## 剧集合并显示
- LibraryPage: 使用 groupSeries 合并剧集, 分季选集详情
- 首页剧集卡片自动链接到媒体库详情

## 全量类名迁移 (43 文件)
- text-slate-* -> text-ink-*/text-sand-*
- text-primary-* -> text-brand-*
- text-white -> text-ink-600
- bg/border-slate-* -> bg/border-sand-*
- 500+ 深色硬编码类名清零

web/src/pages/TasksPage.tsx

@@ -34,23 +34,23 @@ export function TasksPage() {
     }
   }, [])
 
-  if (!snap) return <p className="text-slate-500">加载中…</p>
+  if (!snap) return <p className="text-sand-500">加载中…</p>
 
   const torrents = snap.torrents ?? []
 
   return (
     <div className="space-y-8">
       <header className="flex items-center gap-3">
-        <Activity className="h-6 w-6 text-primary-400" />
-        <h1 className="font-display text-3xl font-bold text-white">实时任务</h1>
+        <Activity className="h-6 w-6 text-brand-500" />
+        <h1 className="font-display text-3xl font-bold text-ink-600">实时任务</h1>
       </header>
 
       <section className="glass-panel">
-        <h2 className="mb-3 font-display text-lg font-semibold text-white">转码任务</h2>
-        {snap.transcodes.length === 0 && <p className="text-slate-500">暂无运行中转码。</p>}
+        <h2 className="mb-3 font-display text-lg font-semibold text-ink-600">转码任务</h2>
+        {snap.transcodes.length === 0 && <p className="text-sand-500">暂无运行中转码。</p>}
         {snap.transcodes.length > 0 && (
           <table className="w-full text-left text-sm">
-            <thead className="text-xs uppercase tracking-wider text-slate-500">
+            <thead className="text-xs uppercase tracking-wider text-sand-500">
               <tr>
                 <th className="py-2">媒体 ID</th>
                 <th>编码器</th>
@@ -61,9 +61,9 @@ export function TasksPage() {
             <tbody>
               {snap.transcodes.map((t) => (
                 <tr key={t.media_id} className="border-t border-white/5">
-                  <td className="py-2 font-mono text-xs text-white">{t.media_id}</td>
-                  <td className="text-slate-300">{t.encoder || 'libx264'}</td>
-                  <td className="text-slate-300">{new Date(t.started_at).toLocaleTimeString()}</td>
+                  <td className="py-2 font-mono text-xs text-ink-600">{t.media_id}</td>
+                  <td className="text-ink-100">{t.encoder || 'libx264'}</td>
+                  <td className="text-ink-100">{new Date(t.started_at).toLocaleTimeString()}</td>
                   <td>
                     {t.playlist_ok ? (
                       <span className="rounded border border-emerald-400/40 px-1.5 py-0.5 text-xs text-emerald-400">
@@ -83,11 +83,11 @@ export function TasksPage() {
       </section>
 
       <section className="glass-panel">
-        <h2 className="mb-3 font-display text-lg font-semibold text-white">下载任务</h2>
-        {torrents.length === 0 && <p className="text-slate-500">暂无运行中下载。</p>}
+        <h2 className="mb-3 font-display text-lg font-semibold text-ink-600">下载任务</h2>
+        {torrents.length === 0 && <p className="text-sand-500">暂无运行中下载。</p>}
         {torrents.length > 0 && (
           <table className="w-full text-left text-sm">
-            <thead className="text-xs uppercase tracking-wider text-slate-500">
+            <thead className="text-xs uppercase tracking-wider text-sand-500">
               <tr>
                 <th className="py-2">名称</th>
                 <th>状态</th>
@@ -98,11 +98,11 @@ export function TasksPage() {
             <tbody>
               {torrents.map((t) => (
                 <tr key={t.hash} className="border-t border-white/5 align-top">
-                  <td className="max-w-md truncate py-2 text-white" title={t.name}>
+                  <td className="max-w-md truncate py-2 text-ink-600" title={t.name}>
                     {t.name}
                   </td>
-                  <td className="text-slate-300">{t.state}</td>
-                  <td className="text-slate-300">
+                  <td className="text-ink-100">{t.state}</td>
+                  <td className="text-ink-100">
                     <div className="flex items-center gap-2">
                       <div className="h-1 w-24 overflow-hidden rounded bg-white/10">
                         <div
@@ -113,7 +113,7 @@ export function TasksPage() {
                       {(t.progress * 100).toFixed(1)}%
                     </div>
                   </td>
-                  <td className="text-slate-300">{fmtBytes(t.size)}</td>
+                  <td className="text-ink-100">{fmtBytes(t.size)}</td>
                 </tr>
               ))}
             </tbody>