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/styles/palette.ts

@@ -0,0 +1,23 @@
+/**
+ * 全站配色，取自 Stitch 稿 code.html 的 Tailwind token（screen.png 取样核实）。
+ * uno.config.ts 用它生成 ap-* 类名和 --ap-* CSS 变量；KLineChart 和新闻 iframe 读不到 CSS 变量，直接引用这里的值。
+ */
+export const PALETTE = {
+  bg: "#0a141f",
+  sunken: "#050f19",
+  panelLow: "#131c27",
+  panel: "#17202b",
+  panelHigh: "#212b36",
+  panelHighest: "#2c3641",
+  line: "#3c4a40",
+  faint: "#859489",
+  text: "#d9e3f3",
+  muted: "#bbcabd",
+  brand: "#ffd162",
+  up: "#45e89b",
+  down: "#ffb4ab",
+  warn: "#ff8f1f",
+  // K 线柱体需要更饱和的涨跌色
+  candleUp: "#0ecb81",
+  candleDown: "#f6465d"
+} as const