feat(video-from-script): 集成可灵图像生成器并优化审查流程

- 新增 kling-image-generator.js 作为可灵 API 图像生成模块，支持文生图和图生图
- 在 pipeline.js 中集成可灵生图，支持在 images 阶段使用 kling 模型
- 更新 SKILL.md 文档：简化用户审查流程，支持"自行选图"模式
- 实现模型降级链（gemini → kling → mj → gemini），增强生图容错性
- 扩展 `--image-model` 参数支持，允许在重试时切换模型

.claude/skills/video-from-script/scripts/pipeline.js

@@ -156,7 +156,7 @@ async function phaseImages(manifest, manifestPath, options) {
   if (items.length === 0) { log('images', '无待处理 item，跳过'); return }
 
   const accountConfig = options.accountConfig || {}
-  let model = manifest.imageModel || accountConfig.imageModel || 'gemini'
+  let model = options.imageModel || manifest.imageModel || accountConfig.imageModel || 'gemini'
   const ratio = manifest.format || accountConfig.defaultFormat || '9:16'
 
   // 首尾帧模式：MJ 降级为 Gemini（MJ 出4张候选图无法一一对应首尾帧）
@@ -217,8 +217,22 @@ async function phaseImages(manifest, manifestPath, options) {
           item.file = item.candidates[0]
           log('images', `[${idx}/${items.length}] ${result.files.length} 张候选，默认选第1张`)
         }
+      } else if (model === 'kling') {
+        const { generate: klingGen } = require('./kling-image-generator')
+        const klingOpts = { outputDir: imagesDir, aspectRatio: ratio }
+        if (refs.urls.length > 0) {
+          klingOpts.referenceImageUrl = refs.urls[0]
+        }
+        log('images', `[${idx}/${items.length}] 可灵生图: ${item.imagePrompt.substring(0, 60)}...`)
+        result = await klingGen(item.imagePrompt, klingOpts)
+        if (result.savedFiles && result.savedFiles.length > 0) {
+          item.file = renameGeneratedFile(
+            path.relative(dir, result.savedFiles[0]).replace(/\\/g, '/'),
+            dir, idx, item.keyword, ''
+          )
+        }
       } else {
-        throw new Error(`不支持的模型: ${model}（支持: gemini, mj）`)
+        throw new Error(`不支持的模型: ${model}（支持: gemini, mj, kling）`)
       }
 
       if (item.file) {
@@ -254,6 +268,13 @@ async function phaseImages(manifest, manifestPath, options) {
               mjOpts.styleWeight = 200
             }
             lastResult = await mjGen(item.lastFramePrompt, mjOpts)
+          } else if (model === 'kling') {
+            const { generate: klingGen } = require('./kling-image-generator')
+            lastResult = await klingGen(item.lastFramePrompt, {
+              outputDir: imagesDir,
+              referenceImageUrl: item.url || '',
+              aspectRatio: ratio,
+            })
           }
 
           if (lastResult) {