feat(members): add full member bio, contact info, and service history

Lazy-enriches member profiles on first view via Congress.gov detail API.
Adds office address, phone, official website, congress.gov link, birth
year, terms history, leadership roles, and sponsored/cosponsored counts.
Includes DB migration 0007 for new member columns.

Co-Authored-By: Jack Levy

backend/app/models/member.py

@@ -1,4 +1,4 @@
-from sqlalchemy import Column, String, DateTime
+from sqlalchemy import Column, Integer, JSON, String, DateTime
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 
@@ -18,6 +18,15 @@ class Member(Base):
     district = Column(String(50))
     photo_url = Column(String)
     official_url = Column(String)
+    congress_url = Column(String)
+    birth_year = Column(String(10))
+    address = Column(String)
+    phone = Column(String(50))
+    terms_json = Column(JSON)
+    leadership_json = Column(JSON)
+    sponsored_count = Column(Integer)
+    cosponsored_count = Column(Integer)
+    detail_fetched = Column(DateTime(timezone=True))
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())