Avoid sending landmap data for Falklands.

This is too damn slow. A possible solution is explained in the comment,
but we shouldn't tackle that until we're sure the rest of the game runs
okay.

game/server/mapzones/models.py

@@ -20,6 +20,10 @@ class MapZonesJs(BaseModel):
     class Config:
         title = "MapZones"
 
+    @classmethod
+    def empty(cls) -> MapZonesJs:
+        return MapZonesJs(inclusion=[], exclusion=[], sea=[])
+
 
 class UnculledZoneJs(BaseModel):
     position: LeafletPoint

game/server/mapzones/routes.py

@@ -1,3 +1,5 @@
+import logging
+
 from fastapi import APIRouter, Depends, HTTPException, status
 
 from game import Game
@@ -10,6 +12,20 @@ router: APIRouter = APIRouter(prefix="/map-zones")
 
 @router.get("/terrain", operation_id="get_terrain_zones", response_model=MapZonesJs)
 def get_terrain(game: Game = Depends(GameContext.require)) -> MapZonesJs:
+    if game.theater.terrain.name == "Falklands":
+        # The new high fidelity landmap is far too expensive to send to the UI.
+        # Converting all the points from DCS X/Y to lat/lng and then serializing all
+        # that data takes minutes and gigabytes (!!) of RAM.
+        #
+        # It's not clear how much the rest of Liberation is affected by the landmap
+        # complexity yet. If the rest of the game is tolerable we will need to start
+        # baking images of the landmap that can be used as an overlay in the UI rather
+        # than drawing it from each point.
+        logging.debug(
+            "Not sending landmap to the UI for Falklands because it's too slow"
+        )
+        return MapZonesJs.empty()
+
     zones = game.theater.landmap
     if zones is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND)