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/ingest.py

@@ -0,0 +1,73 @@
+"""API Push 短新闻 ingest 接口的 I/O schema。"""
+from __future__ import annotations
+
+from datetime import datetime
+from typing import Literal
+
+from pydantic import BaseModel, Field, field_validator
+
+
+# 长度上限(commit 1 规划)
+TITLE_MAX = 200
+BODY_MAX = 5000
+EXTERNAL_ID_MAX = 128
+SOURCE_REF_MAX = 64
+AUTHOR_MAX = 255
+TAGS_MAX = 10  # 最多 10 个标签
+TAG_MAX_LEN = 32  # 单个标签最长
+
+
+class IngestPayload(BaseModel):
+    """POST /api/v1/ingest 请求体。
+
+    必填:title + body
+    推荐:external_id(幂等 key)
+    可选:url / source_ref / author / published_at / tags
+    """
+
+    external_id: str | None = Field(default=None, max_length=EXTERNAL_ID_MAX)
+    title: str = Field(min_length=1, max_length=TITLE_MAX)
+    body: str = Field(min_length=1, max_length=BODY_MAX)
+    url: str | None = Field(default=None, max_length=2048)
+    source_ref: str | None = Field(default=None, max_length=SOURCE_REF_MAX)
+    author: str | None = Field(default=None, max_length=AUTHOR_MAX)
+    published_at: datetime | None = None
+    tags: list[str] | None = Field(default=None, max_length=TAGS_MAX)
+
+    @field_validator("title", "body")
+    @classmethod
+    def _strip_and_check(cls, v: str) -> str:
+        v = v.strip()
+        if not v:
+            raise ValueError("must not be empty after strip")
+        return v
+
+    @field_validator("tags")
+    @classmethod
+    def _clean_tags(cls, v: list[str] | None) -> list[str] | None:
+        if v is None:
+            return None
+        out: list[str] = []
+        seen: set[str] = set()
+        for t in v:
+            t = t.strip()
+            if not t:
+                continue
+            if len(t) > TAG_MAX_LEN:
+                raise ValueError(f"tag too long: {t[:16]}...")
+            if t in seen:
+                continue
+            seen.add(t)
+            out.append(t)
+        return out or None
+
+
+class IngestResponse(BaseModel):
+    """POST /api/v1/ingest 响应。"""
+
+    article_id: int
+    content_hash: str
+    status: Literal["created", "duplicate"]
+    # duplicate 时,告知是 L1 / L2 / L3 哪一层命中
+    reason: str | None = None  # 仅 duplicate 时填充
+    matched_external_id: str | None = None  # 仅 L1 命中时填充