fix(members): link sponsors to bills and fix member search

- Poller now fetches bill detail on insert to get sponsor (list endpoint
  has no sponsor data)
- Add backfill_sponsor_ids task + admin endpoint + UI button to fix the
  1,616 existing bills with NULL sponsor_id
- Member name search now matches both "Last, First" and "First Last"
  using split_part() on the stored name column; same fix applied to
  global search
- Load Bill.sponsor relationship eagerly in get_member_bills to prevent
  MissingGreenlet error during Pydantic serialization
- Remove .trim() on search onChange so spaces can be typed

Authored-By: Jack Levy

backend/app/workers/congress_poller.py

@@ -71,8 +71,14 @@ def poll_congress_bills(self):
                 existing = db.get(Bill, bill_id)
 
                 if existing is None:
-                    # Upsert sponsor member if referenced
-                    sponsor_id = _sync_sponsor(db, bill_data)
+                    # Bill list endpoint has no sponsor data — fetch detail to get it
+                    try:
+                        detail = congress_api.get_bill_detail(
+                            current_congress, parsed["bill_type"], parsed["bill_number"]
+                        )
+                        sponsor_id = _sync_sponsor(db, detail.get("bill", {}))
+                    except Exception:
+                        sponsor_id = None
                     parsed["sponsor_id"] = sponsor_id
                     parsed["last_checked_at"] = datetime.now(timezone.utc)
                     db.add(Bill(**parsed))
@@ -165,6 +171,33 @@ def _sync_sponsor(db, bill_data: dict) -> str | None:
     return bioguide_id
 
 
+@celery_app.task(bind=True, name="app.workers.congress_poller.backfill_sponsor_ids")
+def backfill_sponsor_ids(self):
+    """Backfill sponsor_id for all bills where it is NULL by fetching bill detail from Congress.gov."""
+    import time
+    db = get_sync_db()
+    try:
+        bills = db.query(Bill).filter(Bill.sponsor_id.is_(None)).all()
+        total = len(bills)
+        updated = 0
+        logger.info(f"Backfilling sponsors for {total} bills")
+        for bill in bills:
+            try:
+                detail = congress_api.get_bill_detail(bill.congress_number, bill.bill_type, bill.bill_number)
+                sponsor_id = _sync_sponsor(db, detail.get("bill", {}))
+                if sponsor_id:
+                    bill.sponsor_id = sponsor_id
+                    db.commit()
+                    updated += 1
+            except Exception as e:
+                logger.warning(f"Could not backfill sponsor for {bill.bill_id}: {e}")
+            time.sleep(0.1)  # ~10 req/sec, well under Congress.gov 5000/hr limit
+        logger.info(f"Sponsor backfill complete: {updated}/{total} updated")
+        return {"total": total, "updated": updated}
+    finally:
+        db.close()
+
+
 def _update_bill_if_changed(db, existing: Bill, parsed: dict) -> bool:
     """Update bill fields if anything has changed. Returns True if updated."""
     changed = False