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_de.arb

@@ -17,6 +17,8 @@
   "instanceBackupsIn": "Sicherungen: {place}",
   "instanceNoBackups": "Keine Sicherungen",
   "instanceEuropeanUnion": "Europäische Union",
+  "instanceCountryInEu": "{country} (EU)",
+  "instanceSubdivisionOf": "{subdivision}, {country}",
   "accountsTitle": "Konten",
   "accountAdd": "Konto hinzufügen",
   "accountAddSubtitle": "Wähle die Instanz für das Konto, das du hinzufügst.",