halkyon_app: data locations as precise as a country or a state

An operator's DATA_LOCATION and BACKUP_LOCATION may name a subdivision
(ISO 3166-2, US-CA, DE-BY) besides the EU or a country. The app adds
"(EU)" to a member country and the country to a subdivision ("Germany
(EU)", "California, United States", "Bavaria, Germany (EU)"), in
English and German, and shows the most specific flag there is: a
subdivision's own where the flag package has one, else its country's.
Subdivision names come from Unicode CLDR 48.2 (tool/subdivision_names.py),
bundled with their licence, which the app registers.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

packages/halkyon_app/lib/l10n/halkyon_app_localizations_de.dart

@@ -74,6 +74,16 @@ class HalkyonAppLocalizationsDe extends HalkyonAppLocalizations {
   @override
   String get instanceEuropeanUnion => 'Europäische Union';
 
+  @override
+  String instanceCountryInEu(String country) {
+    return '$country (EU)';
+  }
+
+  @override
+  String instanceSubdivisionOf(String subdivision, String country) {
+    return '$subdivision, $country';
+  }
+
   @override
   String get accountsTitle => 'Konten';