Fix FastAPI doc pages.

We can't directly use frozen dataclasses from pydcs in our interface
because pydantic can't process them. Pydantic is able to automatically
convert to our modelview type from the pydcs type though.

game/server/waypoints/models.py

@@ -1,16 +1,15 @@
 from __future__ import annotations
 
-from dcs.mapping import LatLng
-from pydantic.dataclasses import dataclass
+from pydantic import BaseModel
 
 from game.ato import FlightWaypoint
 from game.ato.flightwaypointtype import FlightWaypointType
+from game.server.leaflet import LeafletPoint
 
 
-@dataclass
-class FlightWaypointJs:
+class FlightWaypointJs(BaseModel):
     name: str
-    position: LatLng
+    position: LeafletPoint
     altitude_ft: float
     altitude_reference: str
     is_movable: bool