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_de.arb

@@ -1,5 +1,19 @@
 {
   "@@locale": "de",
+  "guidedSetupTitle": "Setup-Assistent",
+  "guidedSetupIntro": "Beantworte drei Fragen — Ch∆In stellt passende Konfiguration, Modul-Set und Start-Flow zusammen.",
+  "guidedSetupScenario": "Szenario",
+  "guidedSetupIntent": "Aufgabe",
+  "guidedSetupTarget": "Wo läuft es?",
+  "guidedSetupApproval": "Menschlichen Freigabe-Schritt vor dem KI-Schritt verlangen",
+  "guidedSetupDataLocal": "Daten müssen lokal bleiben (air-gapped)",
+  "guidedSetupReviewHeading": "Diesen Plan wird Ch∆In anwenden:",
+  "guidedSetupApply": "Setup übernehmen",
+  "guidedSetupApplied": "Setup übernommen. Schließe mit den Schritten unten ab:",
+  "guidedSetupBack": "Zurück",
+  "guidedSetupNext": "Weiter",
+  "guidedSetupCancel": "Abbrechen",
+  "guidedSetupClose": "Schließen",
   "appTitle": "Ch∆In Studio",
   "navWelcome": "Willkommen",
   "welcomeHeroTitle": "Ch∆In Platform",