Restyle the web UI in a light theme, step 1: theme, top nav, demo trading

Follow the Stitch "Daylight" design: light canvas, white panels with
hairline borders, deep cyan primary, Inter for UI text and JetBrains Mono
for numbers (bundled via @fontsource-variable).

- Override Element Plus variables in one place and derive light/dark
  shades with color-mix; pages use the UnoCSS Tailwind palette.
- Replace the sidebar with a horizontal top navigation bar.
- Rebuild the demo trading page: status panel with metric tiles,
  positions table, and a three-column layout (symbols, plan card,
  open orders and timeline); restyle the analysis drawer.
- Fix the stale risk wording in the trading capital dialog.

web/uno.config.ts

@@ -13,6 +13,13 @@ export default defineConfig({
       important: "#app"
     })
   ],
+  // 字体栈定义在 styles/index.css，Element Plus 与 UnoCSS 共用
+  theme: {
+    fontFamily: {
+      sans: "var(--ap-font-sans)",
+      mono: "var(--ap-font-mono)"
+    }
+  },
   // 自定义规则
   rules: [],
   // 自定义快捷方式
@@ -20,6 +27,7 @@ export default defineConfig({
     "wh-full": "w-full h-full",
     "flex-center": "flex justify-center items-center",
     "flex-x-center": "flex justify-center",
-    "flex-y-center": "flex items-center"
+    "flex-y-center": "flex items-center",
+    "num": "font-mono tabular-nums"
   }
 })