fix(city): persist full city list and re-emit dashboard context on re-selection

- Map cityList rows without coordinates; fall back en/ru/be for display names
- Replace local city cache on sync when opening city screen
- Use SharedFlow + prefs reads so re-selecting the same city (e.g. Minsk) notifies dashboard

Made-with: Cursor

app/src/main/kotlin/org/db3/airmq/features/city/CityViewModel.kt

@@ -51,6 +51,7 @@ class CityViewModel @Inject constructor(
     private fun loadCities() {
         viewModelScope.launch(Dispatchers.IO) {
             val localeLanguage = Locale.getDefault().language
+            cityService.syncCitiesFromRemote(localeLanguage)
             val regions = cityService.getCitiesGroupedByCountry(localeLanguage)
             val selectedCity = cityService.getSelectedCity()
             val hasOnlyDefaultCity = regions.isEmpty()