WIP checkpoint: Presence & status model + endpoints (Redis heartbeat)

backend/app/models/user.py

@@ -1,4 +1,4 @@
-from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, Text
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 
@@ -16,6 +16,10 @@ class User(Base):
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
 
+    # Presence / status columns
+    last_seen_at = Column(DateTime(timezone=True), nullable=True)
+    status_message = Column(Text, nullable=True)
+
     sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
     worlds = relationship("World", back_populates="owner")
     assets = relationship("Asset", back_populates="owner")