Improve security, validation, and isolation checks

Add multiple security and validation improvements across the app:

- Prevent session fixation: regenerate session ID on login and after successful 2FA; tighten session cookie params (Secure, HttpOnly, SameSite=Lax).
- Harden installer: add CSRF checks for install/update flows and use PDO::quote when injecting admin credentials into SQL migration to avoid injection; add csrf_field() to installer templates.
- Template hardening: add safe_url and safe_mailto Twig filters, escape tag names for JS, and add rel="noopener noreferrer" to external links to mitigate XSS/opener risks.
- Domain controller: validate referrer to avoid open redirects, enforce user isolation mode when finding/deleting/updating domains and when assigning notification groups (ensures users only affect their own resources).
- Notification groups: verify channel belongs to group before deleting or toggling to prevent unauthorized access.
- ErrorLog: whitelist allowed sort columns to avoid arbitrary column injection in ORDER BY.
- Routes: move the debug whois route to protected/admin area.

These changes collectively reduce attack surface (XSS, open redirect, session fixation, SQL injection) and enforce proper resource isolation and input validation.

app/Views/domains/view.twig

@@ -98,7 +98,7 @@
                     {% if domain.registrar_url is not empty %}
                     <div>
                         <label class="text-gray-500 dark:text-slate-400 font-medium block mb-0.5">Registrar URL</label>
-                        <a href="{{ domain.registrar_url }}" target="_blank" class="text-blue-600 dark:text-blue-400 hover:text-blue-800 dark:hover:text-blue-300 flex items-center">
+                        <a href="{{ domain.registrar_url|safe_url }}" target="_blank" rel="noopener noreferrer" class="text-blue-600 dark:text-blue-400 hover:text-blue-800 dark:hover:text-blue-300 flex items-center">
                             <i class="fas fa-external-link-alt mr-1" style="font-size: 9px;"></i>
                             Visit
                         </a>
@@ -107,7 +107,7 @@
                     {% if domain.abuse_email is not empty %}
                     <div>
                         <label class="text-gray-500 dark:text-slate-400 font-medium block mb-0.5">Abuse Contact</label>
-                        <a href="mailto:{{ domain.abuse_email }}" class="text-blue-600 dark:text-blue-400 hover:text-blue-800 dark:hover:text-blue-300">
+                        <a href="{{ domain.abuse_email|safe_mailto }}" class="text-blue-600 dark:text-blue-400 hover:text-blue-800 dark:hover:text-blue-300">
                             {{ domain.abuse_email }}
                         </a>
                     </div>