fix waypoint coordinate precedence for cross-platform merge determinism

Author: aman-coder03

mslib/msui/flighttrack.py

@@ -143,12 +143,17 @@ class Waypoint:
     def __init__(self, lat=0., lon=0., flightlevel=0., location="", comments=""):
         self.location = location
 
-        locations = config_loader(dataset='locations')
-        if location in locations:
-            self.lat, self.lon = locations[location]
-        else:
+        # Prefer explicitly provided coordinates (e.g., from server/XML)
+        if lat != 0.0 or lon != 0.0:
             self.lat = lat
             self.lon = lon
+        else:
+            locations = config_loader(dataset='locations')
+            if location in locations:
+                self.lat, self.lon = locations[location]
+            else:
+                self.lat = lat
+                self.lon = lon
 
         self.flightlevel = flightlevel
         self.pressure = thermolib.flightlevel2pressure(flightlevel * units.hft).magnitude