feat(commentary): 双 provider 评论 — Angel(Agnes) + 美团大模型(LongCat)

- 新增 articles.commentary_meituan{_status,_model,_error} 4 列 + commentary_engine
- LlmSetting 加 meituan_api_key/base_url/chat_model/interval_sec/enabled/commentary_prompt
- 新 app/services/llm/providers.py 工厂,支持多 provider 客户端
- enrichment 流程改为 commentary_angel + commentary_meituan 并行(asyncio.gather),
  任一 provider 失败不影响另一个
- enrichment_loop 状态判定:任一 provider 状态不是 ok 都视为待 enrich
- alembic 0004_dual_commentary 迁移
- 前端 Feed 卡片 + ArticleDetail 详情页各加一条'美团评论'卡
- AdminLlmSettings 加美团 provider 配置卡(独立 api_key 编辑器,不回显明文)
- LlmSettingOut.meituan_api_key_set (bool) 替代直接回传 key
- 默认 URL https://api.longcat.chat/openai/v1 / 默认模型 LongCat-2.0-Preview

backend/app/schemas/article.py

@@ -34,8 +34,12 @@ class ArticleListItem(BaseModel):
     fetched_at: datetime
     image_url: str | None = None
     # === 列表预览钩子:点击进详情前的"诱导点" ===
-    commentary: str | None = None  # LLM 点评(列表里截断显示)
+    # 双 provider 评论:Angel(原字段) + 美团(meituan 字段),前端两条都展示
+    commentary: str | None = None  # Angel 评论(列表里截断显示)
     commentary_status: str | None = None  # ok/failed/pending/n/a
+    commentary_meituan: str | None = None  # 美团评论
+    commentary_meituan_status: str | None = None
+    commentary_engine: str | None = None  # angel / meituan / "angel,meituan"
     image_ai_url: str | None = None  # AI 插图(列表里缩略图)
     is_starred: bool = False
 
@@ -66,8 +70,14 @@ class ArticleDetail(BaseModel):
     format_status: str | None = None  # pending/ok/failed/n/a
     classify_status: str | None = None
     image_ai_status: str | None = None
+    # 双 provider 评论
     commentary_status: str | None = None
-    commentary: str | None = None
+    commentary: str | None = None  # Angel
+    commentary_engine: str | None = None
+    commentary_meituan_status: str | None = None
+    commentary_meituan: str | None = None
+    commentary_meituan_model: str | None = None
+    commentary_meituan_error: str | None = None
     entities: dict | None = None
     sentiment: float | None = None
     duplicate_of: int | None = None