refactor(lightbox): modernize to const/let, template literals, drop IIFE

纯现代化重构,行为不变(23 个回归测试全绿作证):
- var → const/let(state、gotoIndex 的 newIndex 用 let,其余 const)
- 循环 for+var+IIFE包装 → for..of/forEach + const(天然捕获迭代变量,
  消除旧 var 循环闭包必须立即执行函数固定变量的写法)
- 字符串拼接 → 模板字面量(counter 文本、transform、width/height)
- 事件处理 function() → 箭头函数(无 this 依赖场景)
- 拆掉外层 (function(){'use strict'; ... })():ES module 作用域已封装,
  IIFE 是历史遗留;辅助函数仍用 function 声明(openLightbox↔closeLightbox
  互递归依赖提升)

几何纯函数(fitCentered/transformFor/originalUrl)已在 geometry.ts,
本文件只剩 DOM 胶水 + state 单例。
This commit is contained in:
xfy 2026-06-24 11:44:06 +08:00
parent aadfed2595
commit 25eacc1c3c

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