fix: send referral notifications to direct bill/member followers

The dispatcher was suppressing all referral-tier events (committee
referrals) for neutral-mode users, regardless of whether they
directly followed a bill or just followed a topic. This meant
directly-followed bills like HR 7711 and S 3853 showed ✓ in
Recent Alerts but no ntfy notification was ever fired.

Now only topic-follow referral events are suppressed for neutral
users (topic follows are loose and noisy). Direct bill follows and
member follows always receive referral events.

Authored-By: Jack Levy

backend/app/workers/notification_dispatcher.py

@@ -110,9 +110,12 @@ def dispatch_notifications(self):
                 db.commit()
                 continue
 
-            # Referral-tier events (committee referrals) are noisy for neutral follows;
-            # pocket_veto and pocket_boost users want them as early warnings
-            if follow_mode == "neutral" and (event.payload or {}).get("milestone_tier") == "referral":
+            # Referral-tier events (committee referrals) are noisy for loose topic follows;
+            # suppress them only for topic-follow events so direct bill/member followers
+            # still get notified when their bill is referred to committee.
+            payload = event.payload or {}
+            is_topic_follow = payload.get("source") == "topic_follow"
+            if follow_mode == "neutral" and payload.get("milestone_tier") == "referral" and is_topic_follow:
                 event.dispatched_at = now
                 db.commit()
                 continue