feat(desktop): 深色 AI 控制台视觉改造 + 工作台仪表盘

桌面端从扁平 dev 工具风改为深色高端 AI 控制台:分层表面 + 紫青强调 + 微光 +
首页仪表盘，提升第一印象与吸引力。

- 设计 tokens: tailwind ink 分层调色板 + glow/card 阴影; index.css 深色基底 +
  品牌渐变 + 深色滚动条
- shell: TopBar(品牌渐变+毛玻璃+发光健康灯) / LeftNav(激活态紫色高亮+左光条) /
  BottomDrawer(深色+状态色)
- 新 views/Home 工作台仪表盘: 渐变 hero + 4 状态卡 + 3 能力卡 + 快速开始(默认首页)
- 画布: TypedNode 深色节点卡; StudioView ReactFlow colorMode=dark + 深色工具栏/面板/
  MiniMap; Inspector 深色表单
- KbView/MemoryView/MemoryPanel/Placeholder 全深色化; 进度条改紫青渐变
- 纯前端改造, npm build✓; 浏览器验证: 仪表盘 + 编排画布深色呈现

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sundynix-desktop/frontend/src/shell/TopBar.tsx

@@ -2,28 +2,27 @@ import type { Identity } from "../lib/api";
 import { useHealth } from "../lib/health";
 
 function Light({ on, label, unknown }: { on?: boolean; label: string; unknown?: boolean }) {
-  const color = unknown ? "bg-gray-300" : on ? "bg-emerald-500" : "bg-rose-500";
+  const dot = unknown ? "bg-slate-600" : on ? "bg-emerald-400 shadow-[0_0_8px_rgba(52,211,153,0.7)]" : "bg-rose-500";
   return (
-    <span className="flex items-center gap-1 text-[11px] text-gray-500" title={label}>
-      <span className={`h-2 w-2 rounded-full ${color}`} />
+    <span className="flex items-center gap-1.5 text-[11px] text-slate-500" title={label}>
+      <span className={`h-1.5 w-1.5 rounded-full ${dot}`} />
       {label}
     </span>
   );
 }
 
-// 顶栏：垂直切换 · 健康灯 · 身份/会话。
-export function TopBar({
-  identity,
-  setIdentity,
-}: {
-  identity: Identity;
-  setIdentity: (id: Identity) => void;
-}) {
+// 顶栏：品牌 · 垂直切换 · 健康灯 · 身份/会话（深色 + 毛玻璃）。
+export function TopBar({ identity, setIdentity }: { identity: Identity; setIdentity: (id: Identity) => void }) {
   const h = useHealth();
   return (
-    <header className="flex h-11 shrink-0 items-center gap-3 border-b bg-white px-3">
-      <span className="font-semibold text-gray-800">sundynix-agentix</span>
-      <select className="rounded border px-2 py-0.5 text-xs text-gray-700" defaultValue="通用版">
+    <header className="flex h-12 shrink-0 items-center gap-3 border-b border-line bg-ink-900/80 px-3 backdrop-blur">
+      <div className="flex items-center gap-2">
+        <div className="flex h-6 w-6 items-center justify-center rounded-md bg-gradient-to-br from-violet-500 to-cyan-500 text-xs font-bold text-white">
+          S
+        </div>
+        <span className="brand-gradient text-sm font-semibold">sundynix-agentix</span>
+      </div>
+      <select className="rounded-md border border-line bg-ink-800 px-2 py-0.5 text-xs text-slate-300" defaultValue="通用版">
         <option>通用版</option>
         <option>法律版</option>
         <option>医疗版</option>
@@ -37,13 +36,13 @@ export function TopBar({
       </div>
       <div className="ml-auto flex items-center gap-2">
         <input
-          className="w-20 rounded border px-2 py-0.5 text-xs"
+          className="w-20 rounded-md border border-line bg-ink-800 px-2 py-1 text-xs text-slate-200 focus:border-violet-500/60 focus:outline-none"
           value={identity.userId}
           onChange={(e) => setIdentity({ ...identity, userId: e.target.value })}
           title="用户"
         />
         <input
-          className="w-24 rounded border px-2 py-0.5 text-xs"
+          className="w-24 rounded-md border border-line bg-ink-800 px-2 py-1 text-xs text-slate-200 focus:border-violet-500/60 focus:outline-none"
           value={identity.sessionId}
           onChange={(e) => setIdentity({ ...identity, sessionId: e.target.value })}
           title="会话"