fix(map): a region is picked on a screen of its own, and a country's map offered once it is picked

The composer showed the map inside its scrolling page, so zooming and
scrolling fought over the wheel. A map question's answer is now a field
that opens the map in the whole window, as a studyset's description is
written, with Save in the app bar; nothing scrolls there, so the wheel
alone zooms. The Prefectures chip stood beside East Asia's countries
before Japan was picked; it now shows once Japan, or a prefecture, is.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/l10n/app_de.arb

@@ -925,6 +925,7 @@
   "mapUnknown": "Diese Landkarte braucht eine neuere Version der App.",
   "mapPickRegion": "Wähle einen Teil der Karte, dann tippe auf die Region, die die Frage beantwortet. Winzige Orte haben einen Ring; wo Ringe dicht liegen, zoome hinein.",
   "mapNonePicked": "Noch keine Region gewählt",
+  "mapPickTitle": "Region wählen",
   "mapNameJapan": "Japan",
   "mapNameWorld": "Welt",
   "mapPrefectures": "Präfekturen",
@@ -951,6 +952,7 @@
   "mapGroupOceania": "Ozeanien",
   "composerPlaceholderQuestion": "Frage hinzufügen",
   "composerLabelRegion": "Antwort",
+  "composerRegionPick": "Tippen, um die Region auf der Karte zu wählen",
 
   "homeStreakTooltip": "Lernserie",
   "homeArrange": "Widgets anordnen",