Fix dashboard startup regressions and mode utilities

utils/doppler.py

@@ -90,7 +90,7 @@ class DopplerTracker:
             return False
 
         try:
-            ts = load.timescale()
+            ts = load.timescale(builtin=True)
             satellite = EarthSatellite(tle[1], tle[2], tle[0], ts)
             observer = wgs84.latlon(latitude, longitude)
         except Exception as e:

utils/ground_station/scheduler.py

@@ -286,10 +286,10 @@ class GroundStationScheduler:
         from utils.satellite_predict import predict_passes as _predict_passes
 
         try:
-            ts = load.timescale()
+            ts = load.timescale(builtin=True)
         except Exception:
             from skyfield.api import load as _load
-            ts = _load.timescale()
+            ts = _load.timescale(builtin=True)
 
         observer = wgs84.latlon(self._lat, self._lon)
         now = datetime.now(timezone.utc)

utils/weather_sat_predict.py

@@ -70,7 +70,7 @@ def predict_passes(
     # patch sys.modules to simulate skyfield being unavailable).
     import skyfield  # noqa: F401
 
-    ts = load.timescale()
+    ts = load.timescale(builtin=True)
     observer = wgs84.latlon(lat, lon)
     t0 = ts.now()
     t1 = ts.utc(t0.utc_datetime() + datetime.timedelta(hours=hours))