Give the specimen invoice a placeholder in every field, not only the required ones

The footer is four columns of three lines, as designed — but the specimen only
filled the fields an invoice legally needs, so two of the four columns came out
empty and it read as a missing footer rather than as missing data. Reported
that way, which is the correct reading of what was on the page.

A specimen exists to show the layout. Every field now carries an obvious
placeholder, so the shape is visible before any real detail has been entered,
and what is still a placeholder is obvious at a glance.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/Services/Billing/SampleInvoice.php

@@ -21,7 +21,28 @@ final class SampleInvoice
     {
         $issuer = CompanyProfile::all();
 
-        foreach (['name' => 'Ihr Firmenwortlaut e.U.', 'address' => 'Musterstraße 1', 'postcode' => '1010', 'city' => 'Wien', 'vat_id' => 'ATU00000000'] as $field => $placeholder) {
+        // Every field a placeholder, not only the required ones. A specimen
+        // exists to show the layout, and a footer with two of its four columns
+        // empty shows a layout that is not there — the first version of this
+        // was read as a missing footer rather than as missing data.
+        $placeholders = [
+            'name' => 'Ihr Firmenwortlaut e.U.',
+            'address' => 'Musterstraße 1',
+            'postcode' => '1010',
+            'city' => 'Wien',
+            'country' => 'Österreich',
+            'phone' => '+43 000 000000',
+            'email' => 'office@ihre-domain.at',
+            'website' => 'www.ihre-domain.at',
+            'register_number' => 'FN 000000a',
+            'register_court' => 'Handelsgericht Wien',
+            'vat_id' => 'ATU00000000',
+            'bank_name' => 'Bank: Ihre Bank',
+            'iban' => 'AT00 0000 0000 0000 0000',
+            'bic' => 'BIC: XXXXATWW',
+        ];
+
+        foreach ($placeholders as $field => $placeholder) {
             if (trim((string) ($issuer[$field] ?? '')) === '') {
                 $issuer[$field] = $placeholder;
             }