feat: integrate login/registration into PurchaseWizard

public/lang/en/auth.json

@@ -1,68 +1,8 @@
 {
-  "failed": "These credentials do not match our records.",
-  "password": "The provided password is incorrect.",
-  "throttle": "Too many login attempts. Please try again in :seconds seconds.",
-  "login": {
-    "title": "Log in",
-    "description": "Enter your email and password below to log in.",
-    "email": "Email address",
-    "email_placeholder": "email@example.com",
-    "password": "Password",
-    "password_placeholder": "Password",
-    "remember": "Remember me",
-    "submit": "Log in",
-    "forgot": "Forgot password?",
-    "no_account": "Don't have an account?",
-    "sign_up": "Sign up"
-  },
-  "register": {
-    "title": "Register",
-    "welcome": "Welcome to Fotospiel – Create your account",
-    "description": "Registration enables access to events, galleries, and personalized features.",
-    "package_name": "Package",
-    "package_description": "Description",
-    "package_price_free": "Free",
-    "package_price": "{{price}} €",
-    "first_name": "First name",
-    "first_name_placeholder": "First name",
-    "last_name": "Last name",
-    "last_name_placeholder": "Last name",
-    "email": "Email address",
-    "email_placeholder": "email@example.com",
-    "address": "Address",
-    "address_placeholder": "Address",
-    "phone": "Phone number",
-    "phone_placeholder": "Phone number",
-    "username": "Username",
-    "username_placeholder": "Username",
-    "password": "Password",
-    "password_placeholder": "Password",
-    "confirm_password": "Confirm password",
-    "confirm_password_placeholder": "Confirm password",
-    "privacy_consent": "I agree to the privacy policy and accept the processing of my personal data.",
-    "submit": "Create account",
-    "has_account": "Already registered?",
-    "login": "Log in",
-    "errors_title": "Registration errors:",
-    "privacy_policy": "Privacy policy",
-    "errors": {
-      "first_name": "First name is required.",
-      "last_name": "Last name is required.",
-      "email": "Email is required.",
-      "address": "Address is required.",
-      "phone": "Phone number is required.",
-      "username": "Username is required.",
-      "password": "Password is required.",
-      "confirm_password": "Confirm password does not match.",
-      "privacy_consent": "You must agree to the privacy policy."
-    }
-  },
-  "header": {
-    "login": "Log in",
-    "register": "Register"
-  },
-  "verification": {
-    "notice": "Please confirm your email address.",
-    "resend": "Resend email"
-  }
+  "login_failed": "Invalid email or password.",
+  "login_success": "You are now logged in.",
+  "registration_failed": "Registration failed.",
+  "registration_success": "Registration successful – proceed with purchase.",
+  "already_logged_in": "You are already logged in.",
+  "failed_credentials": "Invalid credentials."
 }