refactor(video-from-script): 提取轮询重试逻辑为共享工具

提取三个视频生成器中重复的 `pollWithRetry` 函数到共享模块 `video-poll-utils`，消除代码重复。新增两层重试机制：轮询级（处理网络瞬断）和任务级（创建新任务 + 提示词优化）。同时优化 `phase-videos` 中视频状态管理和 manifest 保存逻辑。

.claude/skills/video-from-script/scripts/lib/phase-videos.js

@@ -5,7 +5,6 @@
  * 支持 task ID 恢复：中断后重跑时优先恢复已有任务
  */
 
-const fs = require('fs')
 const path = require('path')
 const { saveManifest, ensureDir, log, getManifestDir } = require('./pipeline-utils')
 
@@ -24,15 +23,15 @@ async function phaseVideos(manifest, manifestPath, options) {
   const videoCandidates = manifest.items.filter(it => {
     if (it.confirmed === false) return false
     if (!it.url || !it.videoPrompt) return false
-    if (['done', 'pending', 'failed'].includes(it.status)) return true
-    return false
+    return ['done', 'pending', 'failed'].includes(it.status)
   })
-  // 对重试 item 自动清理旧视频引用，无需 agent 手动删除
+
+  // 已有视频（本地或 OSS）且状态为 done 的跳过，其余清理后重新生成
   const items = []
   for (const it of videoCandidates) {
-    if (it.video) {
-      if (it.status === 'done') continue       // 已有视频且完成，跳过
-      delete it.video                           // pending/failed 但有旧 video → 清理重来
+    if (it.video || it.videoUrl) {
+      if (it.status === 'done') continue
+      delete it.video
       delete it.videoUrl
       delete it.videoDuration
       delete it.videoTaskId
@@ -70,7 +69,6 @@ async function phaseVideos(manifest, manifestPath, options) {
     }
   }
 
-  // 轮询恢复的任务
   if (recovered.length > 0) {
     log('videos', `尝试恢复 ${recovered.length} 个中断任务...`)
     await Promise.allSettled(
@@ -86,6 +84,7 @@ async function phaseVideos(manifest, manifestPath, options) {
           if (result.file) {
             item.video = path.relative(dir, result.file).replace(/\\/g, '/')
             item.videoDuration = result.duration
+            item.status = 'done'
             delete item.videoTaskId
             log('videos', `  item ${item.id} 恢复成功`)
           }
@@ -94,9 +93,9 @@ async function phaseVideos(manifest, manifestPath, options) {
           delete item.videoTaskId
           needSubmit.push(item)
         }
-        saveManifest(manifestPath, manifest)
       })
     )
+    saveManifest(manifestPath, manifest)
   }
 
   if (needSubmit.length === 0) { log('videos', '全部通过恢复完成'); return }
@@ -110,13 +109,9 @@ async function phaseVideos(manifest, manifestPath, options) {
     const batch = needSubmit.slice(i, i + concurrency)
     const batchResults = await Promise.allSettled(
       batch.map(async (item) => {
-        const images = item.lastFrameUrl
-          ? [item.url, item.lastFrameUrl]
-          : [item.url]
         const extraOpts = item.lastFrameUrl
           ? { aspectRatio: ratio, lastFrameUrl: item.lastFrameUrl, mode: 'pro' }
           : { aspectRatio: ratio }
-
         try {
           const taskId = await Api.create(item.url, item.videoPrompt, extraOpts)
           return { item, taskId, error: null }
@@ -169,14 +164,15 @@ async function phaseVideos(manifest, manifestPath, options) {
     if (val.ok && val.result.file) {
       val.item.video = path.relative(dir, val.result.file).replace(/\\/g, '/')
       val.item.videoDuration = val.result.duration
+      val.item.status = 'done'
       delete val.item.videoTaskId
     } else if (val.item) {
       val.item.status = 'failed'
       val.item.error = val.error || '视频生成未返回文件'
       delete val.item.videoTaskId
     }
-    saveManifest(manifestPath, manifest)
   }
+  saveManifest(manifestPath, manifest)
 
   // 上传视频到 OSS
   const { uploadFile } = require('../oss-upload')
@@ -192,11 +188,9 @@ async function phaseVideos(manifest, manifestPath, options) {
       } catch (err) {
         log('videos', `  ${item.video} 上传失败: ${err.message}`)
       }
-      saveManifest(manifestPath, manifest)
     }
+    saveManifest(manifestPath, manifest)
   }
-
-  saveManifest(manifestPath, manifest)
 }
 
 module.exports = { phaseVideos }