Add resumable US policy news collectors and provenance

Collect official crypto and US policy documents with deterministic screening, full bodies and attachments, bounded retries, and durable history cursors. Preserve publication precision and source identity while keeping new collectors disabled.

Add real Congress, GovInfo, DOJ and Federal Register fixtures, offline capture replay, isolated database validation, and rollout instructions. Validate 982 backend tests, frontend checks, and 57 deployment control tests.

backend/src/alphapulse/api/news.py

@@ -55,6 +55,8 @@ class NewsBrief(BaseModel):
     first_seen_at: datetime
     revision_no: int
     risk: NewsRiskBrief | None = None
+    published_at_precision: str | None = None
+    published_date: str | None = None
 
 
 class NewsPage(BaseModel):
@@ -71,6 +73,7 @@ class NewsDetail(NewsBrief):
 
 
 class Revision(BaseModel):
+    extra: dict | None = None
     revision_no: int
     title: str
     summary: str
@@ -131,7 +134,7 @@ async def list_news(
     items = []
     for news, excerpt, package in rows:
         risk = {'state': package.state} if package else None
-        items.append(NewsBrief.model_validate({**news.__dict__, 'excerpt': excerpt, 'risk': risk}))
+        items.append(NewsBrief.model_validate({**news.__dict__, 'excerpt': excerpt, 'risk': risk, 'published_at_precision': news.extra.get('published_at_precision'), 'published_date': news.extra.get('published_date')}))
     return success(NewsPage(items=items, total=total))
 
 
@@ -154,7 +157,7 @@ async def get_news(news_id: int, session: Annotated[AsyncSession, Depends(get_se
     news = await session.get(NewsItem, news_id)
     if news is None:
         raise HTTPException(status.HTTP_404_NOT_FOUND, "新闻不存在")
-    return success(NewsDetail.model_validate({**news.__dict__, "excerpt": news.content_text[:EXCERPT_LENGTH]}))
+    return success(NewsDetail.model_validate({**news.__dict__, "excerpt": news.content_text[:EXCERPT_LENGTH], "published_at_precision": news.extra.get("published_at_precision"), "published_date": news.extra.get("published_date")}))
 
 
 @router.get("/{news_id}/revisions")