feat(profiles): add private notes field per profile, visible only to owner

app/models.py

@@ -1,6 +1,6 @@
 from datetime import datetime, timezone
 
-from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String
+from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String, Text
 from sqlalchemy.orm import relationship, validates
 
 from app.database import Base
@@ -61,6 +61,7 @@ class Profile(Base):
     nickname = Column(String(64), nullable=False)
     showcase_enabled = Column(default=False, nullable=False)
     showcase_visible = Column(String(16), nullable=False, default="both")
+    notes = Column(Text, nullable=False, default="")
     created_at = Column(DateTime, default=_utcnow)
 
     user = relationship("User", back_populates="profiles")