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/pubspec.yaml

@@ -52,6 +52,9 @@ dependencies:
   # Picks the files to import (and later the images to add), and saves exports
   # on the desktop: flutter.dev's own.
   file_selector: ^1.1.0
+  # Flags of the countries and of the EU where an instance keeps its data,
+  # lipis' flag-icons (MIT, its notice registered by the app).
+  flag: ^7.1.0
   flutter:
     sdk: flutter
   flutter_bloc: ^9.1.1
@@ -173,6 +176,9 @@ flutter:
     - assets/maps/japan_prefectures.geojson
     - assets/maps/world_countries.geojson
     - assets/maps/LICENSE-CLDR.txt
+    # The notice of the flags where instances keep their data (lipis' flag-icons,
+    # through the flag package).
+    - assets/flags/LICENSE-flag-icons.txt
     # The bundled fonts' licences, for the licence list (see assets/fonts/ATTRIBUTION.md).
     - assets/fonts/OFL-NotoSans.txt
     - assets/fonts/OFL-NotoSansCJK.txt