chore: 删除 microDrawChests 中的死代码（glow 变量与 microChestGlow 函数）

world.html

@@ -2821,9 +2821,6 @@ function microChestIcon(t) {
 function microChestColor(t) {
   return ({ copper: '#c8854a', silver: '#cfd6e0', gold: '#ffd23f', diamond: '#7ad7ff' })[t] || '#ffd23f';
 }
-function microChestGlow(tier) {
-  return ({ common: '#9aa4b2', rare: '#4aa3ff', epic: '#b46bff', legendary: '#ffb13f' })[tier] || '#9aa4b2';
-}
 function microChestEmoji(tier) {
   return ({ common: '📦', rare: '🎁', epic: '🧰', legendary: '💠' })[tier] || '📦';
 }
@@ -2859,7 +2856,6 @@ function microDrawChests(c) {
   const t = microState.animTime;
   microChests.forEach(ch => {
     const sp = microCellToScreen(ch.cell_i + 0.5, ch.cell_j + 0.5);
-    const glow = microChestGlow(ch.tier);
     // 主体：优先使用俯视图 PNG，未加载成功则回退 emoji
     const imgUrl = microChestTopImage(ch.tier);
     const img = imgUrl ? getChestImage(imgUrl) : null;