refactor: use filesystem notifier instead of SMTP

Solo-admin setup; enrollment codes in config/notification.txt. Drop 0012 SMTP/secret files.

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

config/configuration.yml

@@ -1,6 +1,6 @@
 ---
 # Authelia configuration — secrets via template files under /secrets/
-# SMTP username/password/sender: files in /secrets/smtp_*.txt (see README)
+# Notifier: filesystem (solo admin; codes in /config/notification.txt)
 
 server:
   address: 'tcp://:9091'
@@ -72,15 +72,5 @@ storage:
 
 notifier:
   disable_startup_check: false
-  smtp:
-    address: 'submissions://ha01s019.org-dns.com:465'
-    timeout: '15s'
-    username: {{ secret "/secrets/smtp_username.txt" | mindent 0 "|" | msquote }}
-    password: {{ secret "/secrets/smtp_password.txt" | mindent 0 "|" | msquote }}
-    sender: {{ secret "/secrets/smtp_sender.txt" | mindent 0 "|" | msquote }}
-    identifier: 'auth.schwenk.online'
-    subject: '[Authelia] {title}'
-    startup_check_address: 'cuidas@gmail.com'
-    disable_require_tls: false
-    disable_starttls: false
-    disable_html_emails: false
+  filesystem:
+    filename: '/config/notification.txt'