feat(ingest): API Push 短新闻接口层

- POST /api/v1/ingest:鉴权(X-Ingest-Token) + 限速(每 token 2 篇/秒,
  Redis 滑动桶,INGEST_RATE_PER_SEC 可调) + 三层去重(L1 external_id /
  L2 content_hash / L3 DB UNIQUE 兜底,均带 reason)
- 写入字段:is_short_news=True、translation/format/image_ai_status='n/a'、
  classify_status=(有 tags?'ok':'pending')、commentary_{angel,meituan}_status='pending'、
  body_zh_text=body_text(走统一路径,前端/prompt 不用改)
- services/fetchers/api_push.py:compute_content_hash + synthesize_url +
  normalize_published_at + build_initial_status 纯函数
- schemas/ingest.py:IngestPayload(title 1-200/body 1-5000/tags 去重去空) +
  IngestResponse(article_id/content_hash/status/reason/matched_external_id)
- admin.py:POST/GET/DELETE /admin/sources/{id}/ingest-tokens — owner 生成
  (raw_token 仅一次性返回)、列出、撤销
- schemas/article.py:ArticleListItem 加 is_short_news/source_ref;
  ArticleDetail 加 is_short_news/source_ref/external_id
- main.py:挂 ingest router;config.py + .env.example:ingest_rate_per_sec 默认 2

短新闻由 commit 1 enrichment_loop 自动接管 classify + 双 provider commentary,
跳过 format/image。

backend/app/schemas/article.py

@@ -41,6 +41,9 @@ class ArticleListItem(BaseModel):
     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)
+    # === API Push 短新闻标识 ===
+    is_short_news: bool = False
+    source_ref: str | None = None
     is_starred: bool = False
     is_read: bool = False
 
@@ -84,6 +87,10 @@ class ArticleDetail(BaseModel):
     duplicate_of: int | None = None
     published_at: datetime | None = None
     fetched_at: datetime
+    # === API Push 短新闻标识 ===
+    is_short_news: bool = False
+    source_ref: str | None = None
+    external_id: str | None = None  # 调用方幂等 key
     is_starred: bool = False
     is_read: bool = False