fix(core): 脚本 agent 再兼容 lines/caption 变体,补全旁白漏空

豆包不同型号吐不同 schema:Lite 用 dialogue(字符串)+subtitle;Pro 用
lines:[{role,content}]+caption。上一版只认 dialogue/subtitle,导致 Pro 变体
画面能填、旁白仍空。normalize_draft 再扩容:
- 口播来源并入 lines(每项 content/line/text)、voiceover;subtitle/caption 兜底
- 画面来源并入 visual_description
新增 lines/caption 变体回归用例,全套 22 测试通过。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/backend/apps/ai/tests.py

@@ -31,6 +31,26 @@ class NormalizeDraftTests(SimpleTestCase):
         self.assertEqual(draft["segments"][0]["narration"], "卡裆太社死！")
         self.assertEqual(draft["segments"][0]["visual"], "更衣室扯卡裆旧裤")
 
+    def test_lines_and_caption_variant_fills_narration(self):
+        """另一种变体(Doubao-Seed-2.0-P):shots 用 lines:[{role,content}] 放口播、caption 放字幕。
+        必须把 lines 的 content 当对白/旁白,caption 兜底,而不是只填画面留旁白空。"""
+        raw = json.dumps({
+            "ScriptDraft": {
+                "basicInfo": {"totalDuration": 30, "aspectRatio": "9:16"},
+                "shots": [
+                    {"shotNo": 1, "scene": "化妆台两闺蜜", "lines": [{"role": "女主", "content": "防晒泛白太尴尬！"}, {"role": "闺蜜", "content": "试试这个！"}], "caption": "防晒踩雷？"},
+                    {"shotNo": 2, "scene": "手背挤膏体", "lines": [{"role": "闺蜜", "content": "质地清透不泛白"}], "caption": "清透质地"},
+                ],
+            }
+        }, ensure_ascii=False)
+        draft = normalize_draft(raw, aspect_ratio="9:16", total_duration=30)
+        self.assertEqual(len(draft["segments"]), 2)
+        for seg in draft["segments"]:
+            self.assertTrue(seg["narration"], "旁白不应为空")
+            self.assertTrue(seg["visual"], "画面不应为空")
+        self.assertIn("防晒泛白太尴尬", draft["segments"][0]["narration"])
+        self.assertEqual(len(draft["segments"][0]["dialogue"]), 2)  # lines→结构化对白
+
     def test_string_dialogue_not_iterated_as_chars(self):
         """dialogue 为整句字符串时,要当作旁白而不是逐字符遍历。"""
         raw = json.dumps({