refactor: clean up earth brand component wiring

frontend/public/earth/css/info-panel.css

@@ -86,13 +86,11 @@
 }
 
 .hud-panel-info .earth-brand--en .earth-brand__subtitle {
-  font-size: calc(0.84rem * var(--hud-scale));
   line-height: 1.26;
   letter-spacing: 0.01em;
 }
 
 .hud-panel-info .earth-brand--en .earth-brand__description {
-  font-size: calc(0.66rem * var(--hud-scale));
   line-height: 1.24;
   letter-spacing: 0.045em;
 }

frontend/public/earth/js/brand.js

@@ -1,3 +1,5 @@
+const DEFAULT_BRAND_LANGUAGE = "zh";
+
 const BRANDS = {
   zh: {
     ariaLabel: "智能星球计划品牌标识",
@@ -15,11 +17,11 @@ const BRANDS = {
   },
 };
 
-function getBrandConfig(variant = "zh") {
-  return BRANDS[variant] ?? BRANDS.zh;
+function getBrandConfig(variant = DEFAULT_BRAND_LANGUAGE) {
+  return BRANDS[variant] ?? BRANDS[DEFAULT_BRAND_LANGUAGE];
 }
 
-export function renderBrand(variant = "zh") {
+export function renderBrand(variant = DEFAULT_BRAND_LANGUAGE) {
   const config = getBrandConfig(variant);
 
   return `
@@ -45,11 +47,7 @@ export function renderBrand(variant = "zh") {
   `.trim();
 }
 
-export function mountBrand(target, variant = "zh") {
+export function mountBrand(target, variant = DEFAULT_BRAND_LANGUAGE) {
   if (!target) return;
   target.innerHTML = renderBrand(variant);
 }
-
-export function getBrandVariants() {
-  return Object.keys(BRANDS);
-}

frontend/public/earth/js/main.js

@@ -855,10 +855,7 @@ export function init() {
   simplex = createNoise3D();
   updateHudScale();
   const brandRoot = document.getElementById("brand-root");
-  mountBrand(
-    brandRoot,
-    HUD_CONFIG.brandLanguage || "zh",
-  );
+  mountBrand(brandRoot, HUD_CONFIG.brandLanguage);
 
   scene = new THREE.Scene();
   camera = new THREE.PerspectiveCamera(