feat(studio): show module origin store ('from <store>')

StoreItem gains source (mapped from StoreEntry.source); the store grid
shows a 'from <store>' label for operator-added stores (bundled seed
unlabelled). Foundation for grouping by store. EN+DE l10n.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/l10n/app_localizations_de.dart

@@ -15,6 +15,11 @@ class AppLocalizationsDe extends AppLocalizations {
   String get errModuleDownloadHint =>
       'Die Bundle-URL des Moduls ist nicht erreichbar (Statuscode unten). Der Hub läuft — URL/Host korrigieren oder anderen Store wählen.';
 
+  @override
+  String storeFromSource(String store) {
+    return 'aus $store';
+  }
+
   @override
   String get guidedSetupTitle => 'Setup-Assistent';