Notify transfer owners when files enter grace period.

Send grace-entered and countdown emails to owners alongside recipient grace milestones so unpaid transfers get clear wallet top-up reminders before deletion.

Co-authored-by: Cursor <cursoragent@cursor.com>

resources/views/mail/notifications/transfer-recipient.blade.php

@@ -23,6 +23,11 @@
             @endif
         </p>
     @elseif($milestone === 'grace')
+        <div class="highlight-box highlight-box-warning" style="margin-top:0;">
+            <p class="highlight-box-text">Grace period</p>
+            <p class="highlight-box-subtext">Download soon</p>
+        </div>
+
         <h1 class="email-title">Download before these files are removed</h1>
         <p class="email-text">
             The transfer <strong>{{ $transfer->title }}</strong> is in a grace period.