billscroll should now remember user's position across devices

src/apps/drama/models.py

@@ -83,6 +83,25 @@ class GameEvent(models.Model):
         return f"[{self.timestamp:%Y-%m-%d %H:%M}] {actor} → {self.verb}"
 
 
+class ScrollPosition(models.Model):
+    user = models.ForeignKey(
+        settings.AUTH_USER_MODEL, on_delete=models.CASCADE,
+        related_name="scroll_positions",
+    )
+    room = models.ForeignKey(
+        "epic.Room", on_delete=models.CASCADE,
+        related_name="scroll_positions",
+    )
+    position = models.PositiveIntegerField(default=0)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        unique_together = [("user", "room")]
+
+    def __str__(self):
+        return f"{self.user.email} @ {self.room.name}: {self.position}px"
+
+
 def record(room, verb, actor=None, **data):
     """Record a game event in the drama log."""
     return GameEvent.objects.create(room=room, actor=actor, verb=verb, data=data)