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/celery_app.py

@@ -14,6 +14,7 @@ celery_app = Celery(
         "app.workers.llm_processor",
         "app.workers.news_fetcher",
         "app.workers.trend_scorer",
+        "app.workers.member_interest",
     ],
 )
 
@@ -35,6 +36,7 @@ celery_app.conf.update(
         "app.workers.llm_processor.*": {"queue": "llm"},
         "app.workers.news_fetcher.*": {"queue": "news"},
         "app.workers.trend_scorer.*": {"queue": "news"},
+        "app.workers.member_interest.*": {"queue": "news"},
     },
     task_queues=[
         Queue("polling"),
@@ -58,5 +60,13 @@ celery_app.conf.update(
             "task": "app.workers.trend_scorer.calculate_all_trend_scores",
             "schedule": crontab(hour=2, minute=0),
         },
+        "fetch-news-active-members": {
+            "task": "app.workers.member_interest.fetch_news_for_active_members",
+            "schedule": crontab(hour="*/12", minute=30),
+        },
+        "calculate-member-trend-scores": {
+            "task": "app.workers.member_interest.calculate_all_member_trend_scores",
+            "schedule": crontab(hour=3, minute=0),
+        },
     },
 )