feat: increase station coordinate precision to 5 decimals

Station lat/lon was stored rounded to 4 decimals (~11 m). Bump to 5 decimals (~1.1 m), slightly better than GPS hardware accuracy without showing noise.

- SettingsRepo.setStationPosition: round(4) -> round(5)
- QthConverter.qthToPosition: round(4) -> round(6) so 10-char locators fully roundtrip
- Update QthConverterTest expected values to 6-decimal precision

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/SettingsRepo.kt

@@ -213,8 +213,8 @@ class SettingsRepo(
     }
 
     private fun setStationPosition(latitude: Double, longitude: Double, altitude: Double, locator: String) {
-        val newLat = latitude.round(4)
-        val newLon = longitude.round(4)
+        val newLat = latitude.round(5)
+        val newLon = longitude.round(5)
         val newAlt = altitude.round(1)
         val timestamp = System.currentTimeMillis()
         println("Received new Position($newLat, $newLon, $newAlt) & Locator $locator")