feat: zero-config first run — in-browser admin bootstrap + auto-generated secrets

Fresh installs need nothing in .env. See PR description for the full feature.

frontend/src/i18n/locales/de.json

@@ -3462,6 +3462,30 @@
     "regenerateToken": "Link neu generieren",
     "tokenRegenerated": "Kundenzugangs-Link neu generiert"
   },
+  "setup": {
+    "title": "Willkommen bei PicPeak",
+    "subtitle": "Erstellen Sie Ihr Administrator-Konto, um loszulegen",
+    "tokenLabel": "Setup-Token",
+    "tokenPlaceholder": "Einmaligen Setup-Token einfügen",
+    "tokenHint": "Wird beim ersten Start in den Server-Logs ausgegeben (auch in data/SETUP_TOKEN gespeichert).",
+    "tokenRequired": "Der Setup-Token ist erforderlich",
+    "tokenLocationHint": "Nicht gefunden? Führen Sie aus: docker compose logs backend | grep -i \"setup token\"",
+    "emailLabel": "E-Mail-Adresse",
+    "emailPlaceholder": "[email protected]",
+    "emailRequired": "E-Mail ist erforderlich",
+    "invalidEmail": "Bitte geben Sie eine gültige E-Mail-Adresse ein",
+    "passwordLabel": "Passwort",
+    "passwordPlaceholder": "Wählen Sie ein sicheres Passwort",
+    "passwordRequired": "Passwort ist erforderlich",
+    "passwordMinLength": "Das Passwort muss mindestens 8 Zeichen lang sein",
+    "confirmLabel": "Passwort bestätigen",
+    "confirmPlaceholder": "Passwort erneut eingeben",
+    "passwordMismatch": "Die Passwörter stimmen nicht überein",
+    "submit": "Admin-Konto erstellen",
+    "success": "Admin-Konto erstellt. Willkommen!",
+    "genericError": "Einrichtung fehlgeschlagen. Bitte versuchen Sie es erneut.",
+    "tooManyAttempts": "Zu viele Versuche. Bitte warten Sie einen Moment und versuchen Sie es erneut."
+  },
   "adminLogin": {
     "title": "Admin-Anmeldung",
     "subtitle": "Melden Sie sich an, um Ihre Fotogalerien zu verwalten",

frontend/src/i18n/locales/en.json

@@ -3358,6 +3358,30 @@
     "fourStarsPlus": "4+ Stars",
     "fiveStarsOnly": "5 Stars Only"
   },
+  "setup": {
+    "title": "Welcome to PicPeak",
+    "subtitle": "Create your administrator account to get started",
+    "tokenLabel": "Setup token",
+    "tokenPlaceholder": "Paste the one-time setup token",
+    "tokenHint": "Printed to the server logs on first start (also saved to data/SETUP_TOKEN).",
+    "tokenRequired": "The setup token is required",
+    "tokenLocationHint": "Can't find it? Run: docker compose logs backend | grep -i \"setup token\"",
+    "emailLabel": "Email address",
+    "emailPlaceholder": "[email protected]",
+    "emailRequired": "Email is required",
+    "invalidEmail": "Please enter a valid email address",
+    "passwordLabel": "Password",
+    "passwordPlaceholder": "Choose a strong password",
+    "passwordRequired": "Password is required",
+    "passwordMinLength": "Password must be at least 8 characters",
+    "confirmLabel": "Confirm password",
+    "confirmPlaceholder": "Re-enter your password",
+    "passwordMismatch": "Passwords do not match",
+    "submit": "Create admin account",
+    "success": "Admin account created. Welcome!",
+    "genericError": "Setup failed. Please try again.",
+    "tooManyAttempts": "Too many attempts. Please wait a moment and try again."
+  },
   "adminLogin": {
     "title": "Admin Login",
     "subtitle": "Sign in to manage your photo galleries",