Fix GPS recovery - update lastUpdateTime on first reading after signal recovery

When GPS signal is lost and recovered, the position estimator's lastUpdateTime
was only being updated on subsequent readings (when isFirstGPSUpdate was false).
This caused the GPS validity timeout check to fail on the first reading after
recovery, resulting in altitude and distance-to-home values getting stuck at zero.

The fix moves the lastUpdateTime update outside the isFirstGPSUpdate check so it
is updated on every GPS reading, including the first one after recovery.

Fixes iNavFlight#11049

Author: sensei-hacker

src/main/navigation/navigation_pos_estimator.c

@@ -256,11 +256,13 @@ void onNewGPSData(void)
                     posEstimator.gps.eph = INAV_GPS_DEFAULT_EPH;
                     posEstimator.gps.epv = INAV_GPS_DEFAULT_EPV;
                 }
-
-                /* Indicate a last valid reading of Pos/Vel */
-                posEstimator.gps.lastUpdateTime = currentTimeUs;
             }
 
+            /* Indicate a last valid reading of Pos/Vel - must be updated even on
+             * first GPS reading after recovery to prevent position estimate from
+             * timing out and getting stuck at zero (fixes issue #11049) */
+            posEstimator.gps.lastUpdateTime = currentTimeUs;
+
             previousLat = gpsSol.llh.lat;
             previousLon = gpsSol.llh.lon;
             previousAlt = gpsSol.llh.alt;