polish(ui): design language uplift - press feedback, brand gradient, header glass, route icon chips, empty states

- button: unified press scale (active:scale-[0.97]), primary gets vertical
  brand gradient + tighter shadow, secondary gains subtle hover shadow
- input/select/textarea: consistent focus border + 1.5px brand ring
- empty states: icon in circular tinted badge with soft ring, larger rhythm
- header: translucent frosted-glass surface (color-mix + backdrop blur),
  per-route lucide icon chip beside page title (desktop), subtitle hidden
  on phones to declutter
- sidebar: active nav icon tinted brand via .nav-active > svg; user card
  avatar gets brand gradient + ring
- dark theme: text-3 contrast raised (#68707e -> #747c8a)
- verified live (headless): h1/chips/glass render on dashboard/timeline/
  assessment/resume; tsc + vite build green; temp instrumentation reverted

sync-server/www/index.html

@@ -9,8 +9,8 @@
     <link rel="icon" href="/icons/pwa-192.png" />
     <link rel="apple-touch-icon" href="/icons/pwa-192.png" />
     <title>足迹 Footprints</title>
-    <script type="module" crossorigin src="/assets/index-DuP8O2p4.js"></script>
-    <link rel="stylesheet" crossorigin href="/assets/index-D9E2kUSE.css">
+    <script type="module" crossorigin src="/assets/index-DH5SEuAI.js"></script>
+    <link rel="stylesheet" crossorigin href="/assets/index-TvH70H3i.css">
   </head>
   <body>
     <div id="root"></div>