fix(mini-program): 修复 ScriptLibraryView 章节数展示为 0 的问题

getChapterCount 优先从 plotJson.stages.outline.beats.length 获取真实章节数（新剧本），
fallback 根据 length 字段估算：short→1章, medium→2章, long→4章。

mini-program/src/pages/main/ScriptLibraryView.vue

@@ -235,7 +235,18 @@ const getTags = (script) => {
   return []
 }
 
-const getChapterCount = (script) => script.chapterCount || script.chapters || 0
+const getChapterCount = (script) => {
+  // 优先从 beats 数组长度获取（Task 1-5 部署后新剧本结构）
+  const beats = script?.plotJson?.stages?.outline?.beats
+  if (Array.isArray(beats) && beats.length > 0) return beats.length
+
+  // Fallback：根据 length 字段估算（老剧本无 beats 数据）
+  const length = script?.length
+  if (length === 'short') return 1
+  if (length === 'medium') return 2
+  if (length === 'long') return 4
+  return 1
+}
 
 const getWordCount = (script) => {
   const count = Number(script.wordCount || 0)