Restyle the web UI as a dark trading terminal

- Single palette (web/src/styles/palette.ts) taken from the Stitch
  design, exposed as ap-* UnoCSS colors and --ap-* CSS variables and
  used for Element Plus dark theme overrides, KLineChart and the news
  iframe; zero radius, JetBrains Mono / Space Grotesk bundled locally
- New sidebar and header layout; trading page, plan card and analysis
  drawer follow the design; other pages use the same panels
- Status API reports today's closed trades, wins and net PnL, shown as
  today's PnL and win rate on the trading page

web/src/components/SkillTree.vue

@@ -126,8 +126,8 @@ function onCollapse(item: TreeItem) {
       >
         <template #default="{ data }">
           <div
-            class="group w-full flex items-center gap-1 overflow-hidden rounded pr-1 text-sm"
-            :class="{ 'opacity-50': !data.data.enabled, 'bg-yellow-100': highlightIds?.includes(data.id) }"
+            class="group w-full flex items-center gap-1 overflow-hidden pr-1 text-sm"
+            :class="{ 'opacity-50': !data.data.enabled, 'bg-ap-brand/15': highlightIds?.includes(data.id) }"
           >
             <span>{{ data.data.kind === "folder" ? "📁" : "📄" }}</span>
             <span class="truncate">{{ data.data.name }}</span>