feat(instance): an instance says where it keeps people's data

Its operator sets DATA_LOCATION and BACKUP_LOCATION in deploy/.env (a
country's code or EU, the backups also none), and instance.info() hands
them on. The first start's tile and Switch account show the flag of
where the data is and the words, as labels ("Data: European Union",
"Backups: Switzerland"), the countries by the world map's CLDR names:
where the disks are, never which law governs. The flags come from the
flag package, which draws flag-icons; its MIT notice joins the licence
list.

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

halkyon_learn_flutter/lib/l10n/app_de.arb

@@ -589,6 +589,11 @@
   "instanceBuiltInTagline": "In der App voreingestellt",
   "instanceAnother": "Andere Instanz",
   "instanceAnotherTagline": "Gib ihre Adresse ein",
+  "instanceDataAndBackupsIn": "Daten und Sicherungen: {place}",
+  "instanceDataIn": "Daten: {place}",
+  "instanceBackupsIn": "Sicherungen: {place}",
+  "instanceNoBackups": "Keine Sicherungen",
+  "instanceEuropeanUnion": "Europäische Union",
   "instanceContinue": "Weiter",
   "instanceAddressRequired": "Gib die Adresse einer Instanz ein.",
   "instanceAddressInvalid": "Das ist keine Adresse.",