feat(core): AI 生成 Agent 化 — 多模型流式脚本 agent + 可插拔 Provider + gpt-image-2 参考图 + 模特库

- 后端·可插拔 Provider 层:通用 OpenAICompatibleProvider(tokenssr 等中转站,base_url+api_key,零改代码换站)+ ModelProvider.api_key
- 后端·脚本 agent:结构化 ScriptDraft 契约 + 加载电商 skill + 出稿/改稿一体对话 agent(3模式/多模型)+ 流式 SSE 端点(DRF SSE renderer)
- 后端·图像:gpt-image-2 参考图出图 + 故事板 @图1@图2@图3 多锚点合成(锁脸锁商品);Seedance 打开 generate_audio
- 后端·模特库:gpt-image-2 生成器(9:16氛围图→16:9白底三视图)+ seed_demo_models 管理命令
- DB·迁移:tokenssr 中转站 + 多模型 seed(豆包/GPT-5.5/Gemini + gpt-image-2);ScriptSegment 结构化字段
- 前端·脚本趴:接真 SSE(工具卡 + 思考流)+ 模型下拉 + 3模式 + 改稿;agentScriptStream
- skills/ecommerce-video-script 电商脚本技能(运行时依赖)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/backend/apps/ai/providers/volcano.py

@@ -1,8 +1,9 @@
 from dataclasses import dataclass
 import base64
+import json
 import uuid
 from io import BytesIO
-from typing import Any
+from typing import Any, Iterator
 
 import requests
 from django.conf import settings
@@ -52,6 +53,57 @@ class VolcanoArkProvider:
         response.raise_for_status()
         return response.json()
 
+    def chat_completion_stream(
+        self,
+        *,
+        model: str,
+        messages: list[dict[str, Any]],
+        endpoint: str = "chat/completions",
+        temperature: float = 0.8,
+        extra_body: dict[str, Any] | None = None,
+    ) -> Iterator[dict[str, Any]]:
+        """流式对话:逐块 yield {type:'delta'|'tool_call'|'done', ...}。
+        OpenAI 兼容 SSE(火山 ARK / 各中转站同构),供脚本 agent 的 SSE 端实时转发。"""
+        if not self.api_key:
+            raise ValueError("api_key is not configured")
+        body: dict[str, Any] = {"model": model, "messages": messages, "stream": True, "temperature": temperature}
+        if extra_body:
+            body.update(extra_body)
+        with requests.post(
+            f"{self.base_url.rstrip('/')}/{endpoint.lstrip('/')}",
+            headers={
+                "Authorization": f"Bearer {self.api_key}",
+                "Content-Type": "application/json",
+                "Accept": "text/event-stream",
+            },
+            json=body,
+            stream=True,
+            timeout=300,
+        ) as response:
+            response.raise_for_status()
+            # SSE 响应常不带 charset,requests 会按 latin-1 解码 → 中文乱码。强制 UTF-8。
+            response.encoding = "utf-8"
+            for raw in response.iter_lines(decode_unicode=True):
+                if not raw or not raw.startswith("data:"):
+                    continue
+                data = raw[5:].strip()
+                if data == "[DONE]":
+                    break
+                try:
+                    chunk = json.loads(data)
+                except ValueError:
+                    continue
+                choices = chunk.get("choices") or []
+                if not choices:
+                    continue
+                delta = choices[0].get("delta") or {}
+                piece = delta.get("content")
+                if piece:
+                    yield {"type": "delta", "text": piece}
+                if delta.get("tool_calls"):
+                    yield {"type": "tool_call", "tool_calls": delta["tool_calls"]}
+        yield {"type": "done"}
+
     @staticmethod
     def extract_text(data: dict[str, Any]) -> str:
         choices = data.get("choices") or []
@@ -113,6 +165,7 @@ class VolcanoArkProvider:
         duration: int = 15,
         resolution: str = "720p",
         reference_images: list[str] | None = None,
+        generate_audio: bool = True,
     ) -> dict[str, Any]:
         if not self.api_key:
             raise ValueError("VOLCANO_ARK_API_KEY is not configured")
@@ -126,7 +179,8 @@ class VolcanoArkProvider:
             "duration": duration,
             "resolution": resolution,
             "watermark": False,
-            "generate_audio": False,
+            # Seedance 直接出音效 + 人物声音(参考生视频);关掉则是哑片。默认开。
+            "generate_audio": generate_audio,
         }
         response = requests.post(
             f"{self.base_url.rstrip('/')}/{endpoint.lstrip('/')}",