feat(video-from-script): 重构工作流为子Agent分步执行并新增提示词模板系统

将视频制作工作流拆分为独立子步骤：分镜 → 图片提示词 → 生图 → 视频提示词 → 生视频 → 成片，每步由子Agent独立执行。引入prompts/目录统一管理提示词模板（分镜.md、图片提示词.md、视频提示词.md），通过account.json的storyboardPrompt/imageStylePrompt/videoStylePrompt字段引用。

变更内容：
- 新增confirmed机制和pipeline.js confirm命令，生图后必须人工确认才能继续
- manifest schema改用shotDesc/narration/duration/directorRef替代旧字段
- 文件命名规则从keyword改为slug（从shotDesc/narration派生）
- 删除旧的storyboard-rules.md和prompt-rules.md
- pipeline.js脚本拆分为lib/目录下的独立模块（cmd-init/cmd-confirm/cmd-validate/phase-*）
- 新增cmd-create-account支持一键创建带prompts目录的账号
- capcut_assemble支持narration字段替代text作为字幕源
- 新增.gitclaude/settings.json权限配置

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

@@ -0,0 +1,104 @@
+/**
+ * Phase: videos — 视频生成（VEO / Grok / Kling）
+ *
+ * 图生视频，批量提交，生成后自动上传 OSS
+ */
+
+const path = require('path')
+const { saveManifest, ensureDir, log, getManifestDir } = require('./pipeline-utils')
+
+async function phaseVideos(manifest, manifestPath, options) {
+  const dir = getManifestDir(manifestPath)
+  const videosDir = path.join(dir, 'videos')
+  ensureDir(videosDir)
+
+  const accountConfig = options.accountConfig || {}
+  const videoModel = manifest.videoModel || accountConfig.videoModel || 'veo3-fast-frames'
+
+  const items = manifest.items.filter(it =>
+    it.status === 'done' && it.confirmed !== false && it.url && it.videoPrompt && !it.video
+  )
+  if (items.length === 0) { log('videos', '无待处理 item，跳过'); return }
+
+  // 选择生成器
+  let generator
+  const modelLower = videoModel.toLowerCase()
+  if (modelLower.includes('grok')) {
+    generator = require('../grok-video-generator')
+  } else if (modelLower.includes('kling')) {
+    generator = require('../kling-video-generator')
+  } else {
+    generator = require('../veo-video-generator')
+  }
+
+  log('videos', `共 ${items.length} 个, 模型: ${videoModel}`)
+
+  const tasks = items.map((item, i) => {
+    const task = {
+      id: item.id || i + 1,
+      prompt: item.videoPrompt,
+      image: item.url,
+      outputDir: videosDir,
+    }
+    if (item.lastFrameUrl) {
+      task.images = [item.url, item.lastFrameUrl]
+      task.lastFrameUrl = item.lastFrameUrl
+    } else {
+      task.images = [item.url]
+    }
+    return task
+  })
+
+  try {
+    const results = await generator.batchGenerate(tasks, {
+      videoModel,
+      aspectRatio: manifest.format || '9:16',
+      outputDir: videosDir,
+      skipManifestWrite: true,
+    })
+
+    for (let i = 0; i < results.length; i++) {
+      const result = results[i]
+      const item = items[i]
+      if (!item) continue
+      if (result.success && result.file) {
+        item.video = path.relative(dir, result.file).replace(/\\/g, '/')
+        item.videoDuration = result.duration
+      } else {
+        item.status = 'failed'
+        item.error = result.error || '视频生成失败'
+        log('videos', `  item ${(item.id || '?')} 失败: ${item.error}`)
+      }
+    }
+  } catch (err) {
+    log('videos', `批量生成失败: ${err.message}`)
+    for (const item of items) {
+      if (!item.video) {
+        item.status = 'failed'
+        item.error = `批量生成异常: ${err.message}`
+      }
+    }
+  }
+
+  // 上传视频到 OSS
+  const { uploadFile } = require('../oss-upload')
+  const videoItems = manifest.items.filter(it => it.video && !it.videoUrl)
+  if (videoItems.length > 0) {
+    log('videos', `上传 ${videoItems.length} 个视频到 OSS...`)
+    for (const item of videoItems) {
+      const videoPath = path.resolve(dir, item.video)
+      try {
+        const { url } = await uploadFile(videoPath)
+        item.videoUrl = url
+        log('videos', `  ${item.video} → OK`)
+      } catch (err) {
+        log('videos', `  ${item.video} 上传失败: ${err.message}`)
+      }
+      saveManifest(manifestPath, manifest)
+    }
+  }
+
+  saveManifest(manifestPath, manifest)
+}
+
+module.exports = { phaseVideos }