feat(interest): add public interest tracking for members of Congress

Adds Google Trends, NewsAPI, and Google News RSS scoring for members,
mirroring the existing bill interest pipeline. Member profiles now show
a Public Interest chart (with signal breakdown) and a Related News panel.

Key changes:
- New member_trend_scores + member_news_articles tables (migration 0008)
- fetch_gnews_articles() added to news_service for unlimited RSS article storage
- Bill news fetcher now combines NewsAPI + Google News RSS (more coverage)
- New member_interest Celery worker with scheduled news + trend tasks
- GET /members/{id}/trend and /news API endpoints
- TrendChart redesigned with signal breakdown badges and bar+line combo chart
- NewsPanel accepts generic article shape (bills and members)

Co-Authored-By: Jack Levy

backend/app/models/__init__.py

@@ -2,6 +2,7 @@ from app.models.bill import Bill, BillAction, BillDocument
 from app.models.brief import BillBrief
 from app.models.follow import Follow
 from app.models.member import Member
+from app.models.member_interest import MemberTrendScore, MemberNewsArticle
 from app.models.news import NewsArticle
 from app.models.setting import AppSetting
 from app.models.trend import TrendScore
@@ -15,6 +16,8 @@ __all__ = [
     "BillBrief",
     "Follow",
     "Member",
+    "MemberTrendScore",
+    "MemberNewsArticle",
     "NewsArticle",
     "AppSetting",
     "TrendScore",