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/workers/news_fetcher.py

@@ -41,9 +41,12 @@ def fetch_news_for_bill(self, bill_id: str):
             bill_number=bill.bill_number,
         )
 
-        articles = news_service.fetch_newsapi_articles(query)
+        newsapi_articles = news_service.fetch_newsapi_articles(query)
+        gnews_articles = news_service.fetch_gnews_articles(query)
+        all_articles = newsapi_articles + gnews_articles
+
         saved = 0
-        for article in articles:
+        for article in all_articles:
             url = article.get("url")
             if not url:
                 continue