feat(studyset): every menu of a studyset offers all of its options

The library's card offered six options, a topic three, the studyset's
own screen all of them. Each now offers the same, from one list: edit,
move, study options, import and export content, reset progress, archive
or unarchive, delete, more info, and for a copy reporting to its author
and its reports and suggestions. Importing runs where the studyset's
blocs are, so from the library or a topic it opens the studyset's
screen, which asks what to import as it opens.

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/src/app/app_router.dart

@@ -86,7 +86,12 @@ GoRouter buildRouter({String initialLocation = RoutePaths.home}) => GoRouter(
                     return MaterialPage<void>(
                       key: ValueKey('studyset-$id'),
                       name: RoutePaths.studyset(id),
-                      child: _studysetScreen(context, id),
+                      child: _studysetScreen(
+                        context,
+                        id,
+                        importOnOpen:
+                            state.uri.queryParameters['import'] == 'content',
+                      ),
                     );
                   },
                 ),
@@ -314,10 +319,15 @@ Widget _stepEditor(
   );
 }
 
-Widget _studysetScreen(BuildContext context, String id) => _inStudyset(
+Widget _studysetScreen(
+  BuildContext context,
+  String id, {
+  bool importOnOpen = false,
+}) => _inStudyset(
   context,
   id,
-  (studyset, all) => StudysetScreen(studyset: studyset, all: all),
+  (studyset, all) =>
+      StudysetScreen(studyset: studyset, all: all, importOnOpen: importOnOpen),
   wayBack: (
     label: AppLocalizations.of(context).studysetBackToLibrary,
     location: RoutePaths.library,