v2.7.4: Named location presets and tappable nearest-airport ticker

Location presets can now optionally be given a name (e.g. "Home"),
shown in the overview instead of the raw coordinates. The
nearest-airport ticker on the Location Presets screen is now
tappable (shown with a thin green border) and adds that airport
directly as a new preset with its name and coordinates, using the
existing local airport database on the SD card - no internet lookup
needed. AirportLookup::findNearest() now also returns the found
airport's own lat/lon for this purpose.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/airport_lookup.h

@@ -7,6 +7,11 @@ namespace AirportLookup {
         char icao[5] = {0};
         char name[32] = {0};
         float distanceKm = 0;
+        // Koordinaten des gefundenen Flughafens selbst (nicht der
+        // abgefragten Position) - z.B. um ihn direkt als Standort-Preset
+        // uebernehmen zu koennen (siehe location_presets_screen.cpp).
+        double lat = 0;
+        double lon = 0;
     };
     Nearest findNearest(double lat, double lon);
 }