feat: remove deprecated AI-optimized deployment script

- Delete deploy_to_hetzner_AI.sh which was superseded by main deployment script
- Remove cache-busting implementation for index_noSIG_AIopt.html
- Clean up unused SFTP deployment workflow with sshpass authentication

src/manual/auth.config.php

@@ -0,0 +1,12 @@
+<?php
+
+// Zentrale Benutzerverwaltung
+// Benutzername => Passwort (Klartext)
+// Für mehr Sicherheit kann später auf gehashte Passwörter umgestellt werden.
+return [
+    'users' => [
+        'summitwave_malte'            => 'M8uN3fZq!c2Lx9Pt',
+        'summitwave_patrick'          => 'S4rK7vBw#h1Dz6Qe',
+        'ellerbrock_konferenztechnik' => 'E9pL2mTy@k5Vg8Rs',
+    ],
+];