fix(game): 修复格子正方形和图片尺寸问题，用setDisplaySize精确控制角色图片占一格

game/mapRenderer.ts

@@ -3,6 +3,7 @@ import {
   MAP_COLS,
   MAP_ROWS,
   GAME_WIDTH,
+  GAME_HEIGHT,
   HUD_HEIGHT,
   PATH_WAYPOINTS,
   COLOR_PATH,
@@ -36,11 +37,12 @@ export function buildPathTiles(
 
 export const PATH_TILES = buildPathTiles(PATH_WAYPOINTS)
 
-/** 计算格子尺寸 */
+/** 计算格子尺寸（正方形格子，取宽高中较小值保证正方形） */
 export function getCellSize() {
-  const cellW = Math.floor(GAME_WIDTH / MAP_COLS)
-  const cellH = Math.floor((720 - HUD_HEIGHT) / MAP_ROWS)
-  return { cellW, cellH }
+  const rawW = Math.floor(GAME_WIDTH / MAP_COLS)          // 80
+  const rawH = Math.floor((GAME_HEIGHT - HUD_HEIGHT) / MAP_ROWS) // 55
+  const cell = Math.min(rawW, rawH)                        // 55 → 正方形
+  return { cellW: cell, cellH: cell }
 }
 
 /**