refactor(script): remove sync endpoint, add thread-pool & timeout

- Remove unused POST /script/generate sync endpoint and frontend generate()
- Move JSON parsing/validation to asyncio.to_thread() to avoid event-loop blocking
- Add 60s asyncio.timeout() around entire script generation pipeline
- Migrate volcengine_provider to unified AsyncArk client

python-api/app/services/script_service.py

@@ -141,89 +141,100 @@ class ScriptService:
         model_router = await get_model_router()
 
         try:
-            # 加载 Prompt
-            system_prompt = load_system_prompt(category, subcategory)
-            if not system_prompt:
-                yield ScriptGenerationEvent(
-                    type="error",
-                    message=f"未找到提示词: category={category}, subcategory={subcategory}",
-                )
-                return
-
-            user_prompt = load_script_user_prompt(
-                topic=f"{category}/{subcategory}",
-                duration=duration,
-            )
-
-            yield ScriptGenerationEvent(
-                type="start",
-                message="准备生成...",
-            )
-
-            full_content = ""
-            has_shown_generating = False
-
-            async for chunk in model_router.generate_stream_with_progress(
-                prompt=user_prompt,
-                system_prompt=system_prompt,
-                model_id=model,
-                task_type="script",
-                temperature=0.7,
-                response_format="json_object",
-            ):
-                if chunk["type"] == "chunk":
-                    chunk_content = chunk.get("content", "")
-                    if not chunk_content:
-                        continue
-                    full_content += chunk_content
-
-                    if not has_shown_generating:
-                        yield ScriptGenerationEvent(
-                            type="generating",
-                            message="正在创作脚本...",
-                        )
-                        has_shown_generating = True
-
-            if not full_content or not full_content.strip():
-                yield ScriptGenerationEvent(
-                    type="error",
-                    message="AI 返回内容为空，请检查模型配置或重试",
-                )
-                return
-
-            success, parsed_data, error_msg = safe_parse_ai_json_response(full_content)
-
-            if not success:
-                yield ScriptGenerationEvent(
-                    type="error",
-                    message=f"脚本解析失败: {error_msg or '无法解析 AI 返回的内容'}",
-                )
-                return
-
-            try:
-                shots_data = validate_and_normalize_shots(parsed_data)
-
-                if not shots_data:
+            async with asyncio.timeout(60):
+                # 加载 Prompt
+                system_prompt = load_system_prompt(category, subcategory)
+                if not system_prompt:
                     yield ScriptGenerationEvent(
                         type="error",
-                        message="AI 返回的分镜数据为空或格式不正确",
+                        message=f"未找到提示词: category={category}, subcategory={subcategory}",
                     )
                     return
 
-                shots = [ScriptShot(**shot) for shot in shots_data]
-
-                yield ScriptGenerationEvent(
-                    type="complete",
-                    message="脚本生成成功",
-                    result=shots,
+                user_prompt = load_script_user_prompt(
+                    topic=f"{category}/{subcategory}",
+                    duration=duration,
                 )
 
-            except Exception as e:
                 yield ScriptGenerationEvent(
-                    type="error",
-                    message=f"分镜数据处理失败: {str(e)}",
+                    type="start",
+                    message="准备生成...",
                 )
 
+                full_content = ""
+                has_shown_generating = False
+
+                async for chunk in model_router.generate_stream_with_progress(
+                    prompt=user_prompt,
+                    system_prompt=system_prompt,
+                    model_id=model,
+                    task_type="script",
+                    temperature=0.7,
+                    response_format="json_object",
+                ):
+                    if chunk["type"] == "chunk":
+                        chunk_content = chunk.get("content", "")
+                        if not chunk_content:
+                            continue
+                        full_content += chunk_content
+
+                        if not has_shown_generating:
+                            yield ScriptGenerationEvent(
+                                type="generating",
+                                message="正在创作脚本...",
+                            )
+                            has_shown_generating = True
+
+                if not full_content or not full_content.strip():
+                    yield ScriptGenerationEvent(
+                        type="error",
+                        message="AI 返回内容为空，请检查模型配置或重试",
+                    )
+                    return
+
+                success, parsed_data, error_msg = await asyncio.to_thread(
+                    safe_parse_ai_json_response, full_content
+                )
+
+                if not success:
+                    yield ScriptGenerationEvent(
+                        type="error",
+                        message=f"脚本解析失败: {error_msg or '无法解析 AI 返回的内容'}",
+                    )
+                    return
+
+                try:
+                    shots_data = await asyncio.to_thread(
+                        validate_and_normalize_shots, parsed_data
+                    )
+
+                    if not shots_data:
+                        yield ScriptGenerationEvent(
+                            type="error",
+                            message="AI 返回的分镜数据为空或格式不正确",
+                        )
+                        return
+
+                    shots = [ScriptShot(**shot) for shot in shots_data]
+
+                    yield ScriptGenerationEvent(
+                        type="complete",
+                        message="脚本生成成功",
+                        result=shots,
+                    )
+
+                except Exception as e:
+                    yield ScriptGenerationEvent(
+                        type="error",
+                        message=f"分镜数据处理失败: {str(e)}",
+                    )
+
+        except asyncio.TimeoutError:
+            yield ScriptGenerationEvent(
+                type="error",
+                message="脚本生成超时，请重试",
+            )
+
         except Exception as e:
             yield ScriptGenerationEvent(
                 type="error",