feat(instance): data locations as precise as a country or a state

halkyon_shared's 96f2d14: 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, and the app adds "(EU)" to a member
country and the country to a subdivision ("Germany (EU)", "California,
United States") under the most specific flag there is. deploy/.env and
the backups' guide say so; a Storage Box is named by its country now.
The package registers its notices (the flags, CLDR's subdivision
names); Learn's own CLDR notice for the world map stays, its
registration renamed to say so.

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

deploy/compose.yaml

@@ -82,8 +82,8 @@ services:
       # The Jellyfin server suggested to people; empty: jellyfin. on the
       # instance's own domain, if one answers there; `none`: none.
       JELLYFIN_URL: ${JELLYFIN_URL:-}
-      # Where people's data and the backups are, which the app shows; empty:
-      # it says nothing.
+      # Where people's data and the backups are, which the app shows: `EU`, a
+      # country (`DE`) or a subdivision (`US-CA`); empty: it says nothing.
       DATA_LOCATION: ${DATA_LOCATION:-}
       BACKUP_LOCATION: ${BACKUP_LOCATION:-}
       # How much room people's files may take, in MiB; empty: the defaults.