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/services/news_service.py

@@ -87,3 +87,52 @@ def fetch_gnews_count(query: str, days: int = 30) -> int:
     except Exception as e:
         logger.error(f"Google News RSS fetch failed: {e}")
         return 0
+
+
+def fetch_gnews_articles(query: str, days: int = 30) -> list[dict]:
+    """Fetch articles from Google News RSS. No rate limit — unlimited source."""
+    import time as time_mod
+    try:
+        encoded = urllib.parse.quote(f"{query} when:{days}d")
+        url = f"{GOOGLE_NEWS_RSS}?q={encoded}&hl=en-US&gl=US&ceid=US:en"
+        time.sleep(1)  # Polite delay
+        feed = feedparser.parse(url)
+        articles = []
+        for entry in feed.entries[:20]:
+            pub_at = None
+            if entry.get("published_parsed"):
+                try:
+                    pub_at = datetime.fromtimestamp(
+                        time_mod.mktime(entry.published_parsed), tz=timezone.utc
+                    ).isoformat()
+                except Exception:
+                    pass
+            source = ""
+            if hasattr(entry, "source") and isinstance(entry.source, dict):
+                source = entry.source.get("title", "")
+            elif entry.get("tags"):
+                source = entry.tags[0].get("term", "") if entry.tags else ""
+            articles.append({
+                "source": source or "Google News",
+                "headline": entry.get("title", ""),
+                "url": entry.get("link", ""),
+                "published_at": pub_at,
+            })
+        return [a for a in articles if a["url"] and a["headline"]]
+    except Exception as e:
+        logger.error(f"Google News RSS article fetch failed: {e}")
+        return []
+
+
+def build_member_query(first_name: str, last_name: str, chamber: Optional[str] = None) -> str:
+    """Build a news search query for a member of Congress."""
+    full_name = f"{first_name} {last_name}".strip()
+    title = ""
+    if chamber:
+        if "senate" in chamber.lower():
+            title = "Senator"
+        else:
+            title = "Rep."
+    if title:
+        return f'"{full_name}" OR "{title} {last_name}"'
+    return f'"{full_name}"'