feat(auth): add remember me option with persistent DB sessions

app/models.py

@@ -21,6 +21,18 @@ class User(Base):
 
     api_keys = relationship("ApiKey", back_populates="user", cascade="all, delete-orphan")
     profiles = relationship("Profile", back_populates="user", cascade="all, delete-orphan")
+    sessions = relationship("UserSession", back_populates="user", cascade="all, delete-orphan")
+
+
+class UserSession(Base):
+    __tablename__ = "user_sessions"
+
+    token = Column(String(64), primary_key=True)
+    user_id = Column(Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False)
+    created_at = Column(DateTime, default=_utcnow)
+    expires_at = Column(DateTime, nullable=True)
+
+    user = relationship("User", back_populates="sessions")
 
 
 class ApiKey(Base):