feat: guided-setup wizard — localized explained options + plain-language plan

Reworks the Setup-Assistent toward the zero-learning-curve bar
(docs/architecture/guided-setup.md, phase 1.1):

- Every scenario/intent/target choice is now a localized option CARD
  with a one-line plain-language explanation of what it configures
  (DE+EN, Sie-form) — replacing the bare dropdowns whose labels were
  English enum humanizations ('Regulated Production', 'This Laptop').
- Three explained steps with a 'Schritt n von 3' progress line
  (stakes → task → environment); the two adaptive toggles move to the
  last step in plain language (no 'air-gapped' jargon).
- The review step renders a localized PLAIN-LANGUAGE summary built
  from 'chain init --answers --plan-json' (the structured SetupPlan) —
  'Ch∆In richtet einen regulierten Betrieb ein: signierte Module
  verlangt · … · geändert wird nur ~/.chain/config.yaml' — instead of
  echoing the CLI's English prose. Warns when an existing config will
  be overwritten. After apply: a plain 'Fertig' + next steps.

flutter analyze clean; widget tests for the step flow + German option
labels. Remaining per plan: clickable follow-up actions, signature
dead-end fix, placement/auto-open, and the LLM free-text path.

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

test/guided_setup_test.dart

@@ -1,30 +1,78 @@
-// Smoke test for the guided-setup wizard: it mounts and renders its
-// first step (three choice dropdowns) without touching the CLI. The
-// `chain init` shell-out only happens on Next/Apply, so mounting is
-// side-effect-free and safe to assert in a widget test.
+// Guided-setup wizard — the three explained answer steps. Verifies
+// that options render as localized cards with their one-line
+// explanation (no English enum humanization) and that Weiter/Zurück
+// walk the steps. The review step calls the CLI (a subprocess) and is
+// out of scope for a widget test.
 
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+
 import 'package:chain_studio/l10n/app_localizations.dart';
 import 'package:chain_studio/widgets/guided_setup_dialog.dart';
 
-void main() {
-  testWidgets('guided setup wizard mounts and shows the first step',
-      (tester) async {
-    await tester.pumpWidget(
-      MaterialApp(
-        locale: const Locale('en'),
-        localizationsDelegates: AppLocalizations.localizationsDelegates,
-        supportedLocales: AppLocalizations.supportedLocales,
-        home: const Scaffold(body: GuidedSetupDialog()),
+Widget _host() => MaterialApp(
+  locale: const Locale('de'),
+  localizationsDelegates: AppLocalizations.localizationsDelegates,
+  supportedLocales: AppLocalizations.supportedLocales,
+  home: Builder(
+    builder: (context) => Scaffold(
+      body: Center(
+        child: ElevatedButton(
+          onPressed: () => GuidedSetupDialog.show(context),
+          child: const Text('open'),
+        ),
       ),
-    );
-    await tester.pump();
+    ),
+  ),
+);
 
-    // Title from l10n + the three scenario/intent/target dropdowns.
-    expect(find.text('Setup assistant'), findsWidgets);
-    expect(find.byType(DropdownButton<String>), findsNWidgets(3));
-    // The "Next" action is present (advances to the review/apply step).
-    expect(find.widgetWithText(FilledButton, 'Next'), findsOneWidget);
+void main() {
+  testWidgets('step 1 shows scenario options in German with explanations', (
+    tester,
+  ) async {
+    await tester.pumpWidget(_host());
+    await tester.tap(find.text('open'));
+    await tester.pumpAndSettle();
+
+    // Step counter + localized (German) scenario labels, not the
+    // English enum humanization.
+    expect(find.text('Schritt 1 von 3'), findsOneWidget);
+    expect(find.text('Regulierter Produktivbetrieb'), findsOneWidget);
+    expect(find.text('Erst mal ausprobieren'), findsOneWidget);
+    // Each option carries its one-line explanation.
+    expect(
+      find.textContaining('menschliche Freigabe vor jedem KI-Schritt'),
+      findsOneWidget,
+    );
+    // No leaked English enum labels.
+    expect(find.text('Regulated Production'), findsNothing);
+    expect(find.text('Trying Out'), findsNothing);
+  });
+
+  testWidgets('Weiter/Zurück walk the three answer steps', (tester) async {
+    await tester.pumpWidget(_host());
+    await tester.tap(find.text('open'));
+    await tester.pumpAndSettle();
+
+    // Step 1 → 2 (task).
+    await tester.tap(find.text('Weiter'));
+    await tester.pumpAndSettle();
+    expect(find.text('Schritt 2 von 3'), findsOneWidget);
+    expect(find.text('Text aus Dokumenten extrahieren'), findsOneWidget);
+
+    // Step 2 → 3 (environment) shows the two plain-language toggles.
+    await tester.tap(find.text('Weiter'));
+    await tester.pumpAndSettle();
+    expect(find.text('Schritt 3 von 3'), findsOneWidget);
+    expect(find.text('Dieser Rechner'), findsOneWidget);
+    expect(
+      find.text('Vor jedem KI-Schritt einen Menschen um Freigabe bitten'),
+      findsOneWidget,
+    );
+
+    // Zurück returns to step 2.
+    await tester.tap(find.text('Zurück'));
+    await tester.pumpAndSettle();
+    expect(find.text('Schritt 2 von 3'), findsOneWidget);
   });
 }