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_en.arb

@@ -70,6 +70,27 @@
   },
   "instanceNoBackups": "No backups",
   "instanceEuropeanUnion": "European Union",
+  "instanceCountryInEu": "{country} (EU)",
+  "@instanceCountryInEu": {
+    "description": "A country of the European Union, where an instance keeps data: Germany (EU).",
+    "placeholders": {
+      "country": {
+        "type": "String"
+      }
+    }
+  },
+  "instanceSubdivisionOf": "{subdivision}, {country}",
+  "@instanceSubdivisionOf": {
+    "description": "A state or region with its country, where an instance keeps data: California, United States.",
+    "placeholders": {
+      "subdivision": {
+        "type": "String"
+      },
+      "country": {
+        "type": "String"
+      }
+    }
+  },
   "accountsTitle": "Accounts",
   "accountAdd": "Add account",
   "accountAddSubtitle": "Choose the instance for the account to add.",