feat(setup): per-feature config step after feature selection

When the chosen features need config the wizard can collect, 'Finish' on
the usage step now advances to a lean config step instead of jumping to
the dashboard:
- Invoicing (if Invoices): company/legal name, address, VAT-ID or tax
  number, IBAN, currency → saved to business-profile + a default bank
  account. Carries the bank/VAT legal disclaimer.
- Email (if reminders/incoming-mail/whatsapp/invoices): SMTP host/port/
  user/pass/from → saved to email_configs.
Each section persists only if started, and 'Skip for now' is always
available — soft settings keep their seeded defaults. en + de strings.

frontend/src/i18n/locales/de.json

@@ -3509,6 +3509,32 @@
     "restoreEntry": "Wechsel von einer anderen PicPeak-Instanz?",
     "restoreEntryHint": "Stellen Sie stattdessen ein .picpeak-Backup wieder her, anstatt neu einzurichten.",
     "restoreIntro": "Laden Sie ein .picpeak-Backup hoch, um eine andere Instanz auf diese zu klonen. Dies ersetzt alles außer dem gerade erstellten Konto.",
+    "config": {
+      "subtitle": "Richten Sie Ihre Funktionen ein",
+      "intro": "Einige Angaben zu den gewählten Funktionen. Was Sie überspringen, behält den Standard und kann später in den Einstellungen festgelegt werden.",
+      "invoicing": "Rechnungsdaten",
+      "invoicingDisclaimer": "Erscheint auf Ihren Rechnungen. Bank-/IBAN- und Mehrwertsteuerangaben liegen in Ihrer Verantwortung — prüfen Sie sie mit Ihrer Bank und Ihrem Treuhänder/Steuerberater.",
+      "companyName": "Firma / rechtlicher Name",
+      "addressLine1": "Strasse und Nummer",
+      "postalCode": "PLZ",
+      "city": "Ort",
+      "countryCode": "Ländercode (z. B. CH)",
+      "currency": "Währung (z. B. CHF)",
+      "vatId": "MwSt-Nummer (oder leer lassen)",
+      "taxId": "Steuernummer (oder MwSt-Nummer)",
+      "iban": "IBAN (für Rechnungszahlungen)",
+      "email": "E-Mail-Versand (SMTP)",
+      "emailHint": "Erforderlich, um Erinnerungen, Rechnungen und Benachrichtigungen zu senden.",
+      "smtpHost": "SMTP-Host",
+      "smtpPort": "Port",
+      "smtpUser": "Benutzername",
+      "smtpPass": "Passwort",
+      "fromEmail": "Absenderadresse",
+      "fromName": "Absendername",
+      "skip": "Vorerst überspringen",
+      "finish": "Einrichtung abschließen",
+      "saveFailed": "Einige Einstellungen konnten nicht gespeichert werden — Sie können sie in den Einstellungen abschließen."
+    },
     "stepOf": "Schritt {{current}} von {{total}}",
     "continue": "Weiter",
     "back": "Zurück",

frontend/src/i18n/locales/en.json

@@ -3405,6 +3405,32 @@
     "restoreEntry": "Migrating from another PicPeak?",
     "restoreEntryHint": "Restore a .picpeak backup instead of setting up fresh.",
     "restoreIntro": "Upload a .picpeak backup to clone another instance onto this one. This replaces everything except the account you just created.",
+    "config": {
+      "subtitle": "Set up your features",
+      "intro": "A few details for the features you picked. Anything you skip keeps its default and can be set later in Settings.",
+      "invoicing": "Invoicing details",
+      "invoicingDisclaimer": "Used on your invoices. Bank/IBAN and VAT details are your responsibility — verify them with your bank and Treuhänder/tax advisor.",
+      "companyName": "Company / legal name",
+      "addressLine1": "Street and number",
+      "postalCode": "Postal code",
+      "city": "City",
+      "countryCode": "Country code (e.g. CH)",
+      "currency": "Currency (e.g. CHF)",
+      "vatId": "VAT ID (or leave blank)",
+      "taxId": "Tax number (or VAT ID)",
+      "iban": "IBAN (for invoice payments)",
+      "email": "Email delivery (SMTP)",
+      "emailHint": "Required to send reminders, invoices and notifications.",
+      "smtpHost": "SMTP host",
+      "smtpPort": "Port",
+      "smtpUser": "Username",
+      "smtpPass": "Password",
+      "fromEmail": "From address",
+      "fromName": "From name",
+      "skip": "Skip for now",
+      "finish": "Finish setup",
+      "saveFailed": "Some settings could not be saved — you can finish them in Settings."
+    },
     "stepOf": "Step {{current}} of {{total}}",
     "continue": "Continue",
     "back": "Back",