Fix remaining code review findings: email transport errors, metadata payload, from-name, pagination

- Email::send(): add curl_error() check so transport failures (timeout,
  DNS, TLS) return a diagnosable error string instead of Unknown error
- Email::send(): strip metadata key from options before array_merge so
  non-API fields are never sent to CyberMail endpoint
- Email::send() + sendEmail(): include from-name in From field using
  RFC 5322 "Name <email>" format so fromName DB setting takes effect
- email-log.php: replace unbounded page-link loop with a windowed
  paginator (first/last 2 pages + ±2 around current) with ellipsis
  gaps — prevents hundreds of anchors rendering at scale

admin/email-log.php

@@ -217,16 +217,30 @@ $statusBadge = [
     </div>
 
     <!-- Pagination -->
-    <?php if ($totalPages > 1): ?>
-    <div style="display:flex;justify-content:center;gap:8px;margin-top:20px;">
-        <?php for ($i = 1; $i <= $totalPages; $i++): ?>
-        <a href="?page=<?= $i ?>&search=<?= urlencode($search) ?>&status=<?= urlencode($statusFilter) ?>&customer=<?= urlencode($customerFilter) ?>"
+    <?php if ($totalPages > 1):
+        $window = 2;
+        $pages  = [];
+        for ($i = 1; $i <= $totalPages; $i++) {
+            if ($i <= $window || $i > $totalPages - $window || abs($i - $page) <= $window) {
+                $pages[] = $i;
+            }
+        }
+        $pages = array_unique($pages);
+        sort($pages);
+        $qs = '&search=' . urlencode($search) . '&status=' . urlencode($statusFilter) . '&customer=' . urlencode($customerFilter);
+    ?>
+    <div style="display:flex;justify-content:center;gap:8px;margin-top:20px;flex-wrap:wrap;">
+        <?php $prev = null; foreach ($pages as $i):
+            if ($prev !== null && $i - $prev > 1): ?>
+            <span style="padding:6px 4px;color:#9CA3AF;">…</span>
+        <?php endif; ?>
+        <a href="?page=<?= $i ?><?= $qs ?>"
            style="padding:6px 12px;border-radius:4px;text-decoration:none;
                   background:<?= $i === $page ? '#FF5E1A' : '#f3f4f6' ?>;
                   color:<?= $i === $page ? 'white' : '#374151' ?>;">
             <?= $i ?>
         </a>
-        <?php endfor; ?>
+        <?php $prev = $i; endforeach; ?>
     </div>
     <?php endif; ?>
 </div>