feat: harden auth flows and server mobile navigation

Add normalized email identity rate limiting for registration and forgot-password requests, and refresh Sentinel status from restart broadcasts.

Rework server sidebars and navbar for mobile menus and active status visibility.

bootstrap/helpers/email.php

@@ -0,0 +1,20 @@
+<?php
+
+use Illuminate\Support\Str;
+
+function normalize_email_identity(?string $email): ?string
+{
+    if (blank($email) || ! str_contains($email, '@')) {
+        return null;
+    }
+
+    [$localPart, $domain] = explode('@', Str::lower($email), 2);
+    $localPart = Str::before($localPart, '+');
+    $localPart = str_replace('.', '', $localPart);
+
+    if (blank($localPart) || blank($domain)) {
+        return null;
+    }
+
+    return $localPart.'@'.$domain;
+}