feat: roll-call votes + granular alert filter fix (v0.9.5)

Roll-call votes:
- Migration 0017: bill_votes + member_vote_positions tables
- Fetch vote XML directly from House Clerk / Senate LIS URLs
  embedded in bill actions recordedVotes objects
- GET /api/bills/{id}/votes triggers background fetch on first view
- VotePanel on bill detail: yea/nay bar, result badge, followed
  member positions with Sen./Rep. title, party badge, and state

Alert filter fix:
- _should_dispatch returns True when alert_filters is None so users
  who haven't saved filters still receive all notifications

Authored-By: Jack Levy

backend/app/models/__init__.py

@@ -11,6 +11,7 @@ from app.models.setting import AppSetting
 from app.models.trend import TrendScore
 from app.models.committee import Committee, CommitteeBill
 from app.models.user import User
+from app.models.vote import BillVote, MemberVotePosition
 
 __all__ = [
     "Bill",
@@ -18,12 +19,14 @@ __all__ = [
     "BillDocument",
     "BillBrief",
     "BillNote",
+    "BillVote",
     "Collection",
     "CollectionBill",
     "Follow",
     "Member",
     "MemberTrendScore",
     "MemberNewsArticle",
+    "MemberVotePosition",
     "NewsArticle",
     "NotificationEvent",
     "AppSetting",