fix(study): a map question names none of Japan's parts before it is answered

The chips above Japan's map (Hokkaidō, Tōhoku, Kantō …) showed while a
prefecture's question was answered: Hokkaidō's and Okinawa's chip was
the answer itself, and the others named the region the prefecture lies
in. A study card now offers them only once checked; tapping the map
still opens the part tapped. The world's continents keep their chips:
shortcuts no question asks for. Writing a question offers them all, as
before.

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/test/feature/geo_map/widget/region_map_test.dart

@@ -28,6 +28,7 @@ void main() {
     String? right,
     String? wrong,
     bool readOnly = false,
+    bool namesCountryParts = true,
   }) async {
     tester.view
       ..physicalSize = const Size(400, 640)
@@ -52,6 +53,7 @@ void main() {
                 selected: picked.lastOrNull,
                 right: right,
                 wrong: wrong,
+                namesCountryParts: namesCountryParts,
                 onRegionTapped: readOnly
                     ? null
                     : (code) => setState(() => picked.add(code)),
@@ -102,6 +104,35 @@ void main() {
 
   const tokyo = (139.69, 35.69);
 
+  testWidgets("while answering, Japan's parts have no chips, which would "
+      "name the answer or where it lies; the map opens them at a tap, and the "
+      "world's continents keep theirs", (tester) async {
+    final picked = await show(
+      tester,
+      countryTaps: CountryTaps.open,
+      // The questions studied, all prefectures: on the whole of Japan.
+      around: {'JP-13', 'JP-27'},
+      namesCountryParts: false,
+    );
+
+    expect(back('East Asia'), findsOneWidget);
+    expect(chip('Hokkaidō'), findsNothing);
+    expect(chip('Kantō'), findsNothing);
+    await tapAt(tester, tokyo);
+    expect(find.text('Kantō'), findsOneWidget);
+    await tapAt(tester, tokyo);
+    expect(picked, ['JP-13']);
+
+    await tester.tap(back('Japan'));
+    await tester.pumpAndSettle();
+    expect(chip('Okinawa'), findsNothing);
+    await tester.tap(back('East Asia'));
+    await tester.pumpAndSettle();
+    await tester.tap(back('World'));
+    await tester.pumpAndSettle();
+    expect(chip('Europe'), findsOneWidget);
+  });
+
   testWidgets('Japan is picked in East Asia, and once it is, a chip opens '
       'its prefectures in layers; Back goes up one', (tester) async {
     final picked = await show(tester);