feat(studio): guided-setup wizard (reuses chain init engine)

A Welcome 'Setup assistant' button opens a wizard that collects
scenario / intent / target (+ approval & data-local toggles), then calls
`chain init --answers` to preview the assembled plan and `--apply --force`
to write the config — reusing the Rust deterministic engine, no logic
duplicated. New SystemActions.chainInit; copyable errors via
showFaiProcessError; EN+DE l10n. analyze clean; smoke test + existing
welcome/sidebar tests pass.

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

lib/l10n/app_localizations_en.dart

@@ -8,6 +8,52 @@ import 'app_localizations.dart';
 class AppLocalizationsEn extends AppLocalizations {
   AppLocalizationsEn([String locale = 'en']) : super(locale);
 
+  @override
+  String get guidedSetupTitle => 'Setup assistant';
+
+  @override
+  String get guidedSetupIntro =>
+      'Answer three questions and Ch∆In assembles a tailored config, module set and starter flow.';
+
+  @override
+  String get guidedSetupScenario => 'Scenario';
+
+  @override
+  String get guidedSetupIntent => 'Task';
+
+  @override
+  String get guidedSetupTarget => 'Where will it run?';
+
+  @override
+  String get guidedSetupApproval =>
+      'Require a human approval step before the AI step';
+
+  @override
+  String get guidedSetupDataLocal =>
+      'Data must stay local (air-gapped posture)';
+
+  @override
+  String get guidedSetupReviewHeading => 'This is the plan Ch∆In will apply:';
+
+  @override
+  String get guidedSetupApply => 'Apply setup';
+
+  @override
+  String get guidedSetupApplied =>
+      'Setup applied. Finish with the steps below:';
+
+  @override
+  String get guidedSetupBack => 'Back';
+
+  @override
+  String get guidedSetupNext => 'Next';
+
+  @override
+  String get guidedSetupCancel => 'Cancel';
+
+  @override
+  String get guidedSetupClose => 'Close';
+
   @override
   String get appTitle => 'Ch∆In Studio';