style(hub): refine light theme contrast and theme-aware fullscreen UI

Co-authored-by: Cursor <cursoragent@cursor.com>

manual_trading_hub/static/theme.js

@@ -1,7 +1,7 @@
 /** 中控主题：暗色（默认）/ 亮色，localStorage hub-theme */
 (function (global) {
   const KEY = "hub-theme";
-  const META = { dark: "#0b0e18", light: "#e8eef5" };
+  const META = { dark: "#0b0e18", light: "#d4dde8" };
 
   function normalize(theme) {
     return theme === "light" ? "light" : "dark";