A ticket reference is never re-issued, and notifications name their recipient (#224, #228)

#224 — the next number came from the live rows, so deleting a ticket freed its
reference and two tickets could both be QAX-0004. An old email then points at a
different ticket than it did. The sequence is now held on the group and only ever
moves forward.

#228 — ticketing notifications carried no user, so the Notification Log showed
the message type where the recipient belongs and the per-person opt-out was
ignored: somebody who had opted out still received them.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ec3REU4LQmhuchRRn6dZHk

src/Http/Controllers/TicketController.php

@@ -515,12 +515,13 @@ class TicketController extends Controller
 
         if ($handedOver) {
             $agent = \App\Models\User::find($newAssignee);
-            $email = trim((string) ($agent?->email ?? ''));
 
-            if ($email !== '') {
+            // The agent, not their address — see TicketingNotifier::deliver().
+            // A bare string loses to_user_id and to_name and skips the opt-out.
+            if ($agent) {
                 \Dashboard\Ticketing\Support\TicketingNotifier::deliver(
                     \Dashboard\Ticketing\Support\TicketingNotifier::ASSIGNED,
-                    $email,
+                    $agent,
                     "[{$ticket->number}] Assigned to you: {$ticket->title}",
                     '<p>'.e(Auth::user()?->name ?? 'Somebody').' assigned this ticket to you.</p>'
                         .'<p><a href="'.e(route('ticketing.show', $ticket->id)).'">View the ticket</a></p>',