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- Delete deploy_to_hetzner_AI.sh which was superseded by main deployment script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.php

@@ -0,0 +1,87 @@
+<?php
+
+session_start();
+
+const SW_MANUAL_LOG_FILE = __DIR__ . '/logs/access.log';
+
+function sw_load_users(): array {
+    $cfgPath = __DIR__ . '/auth.config.php';
+    if (!file_exists($cfgPath)) {
+        return [];
+    }
+    $cfg = require $cfgPath;
+    return $cfg['users'] ?? [];
+}
+
+function sw_verify_login(string $username, string $password): bool {
+    $users = sw_load_users();
+    if (!isset($users[$username])) {
+        return false;
+    }
+    $expected = (string)$users[$username];
+    return hash_equals($expected, $password);
+}
+
+function sw_current_user(): ?string {
+    return $_SESSION['sw_manual_user'] ?? null;
+}
+
+function sw_require_login(): void {
+    if (!sw_current_user()) {
+        header('Location: login.php');
+        exit;
+    }
+}
+
+function sw_record_login(string $username): void {
+    $dir = dirname(SW_MANUAL_LOG_FILE);
+    if (!is_dir($dir)) {
+        @mkdir($dir, 0775, true);
+    }
+    $ts   = (new DateTimeImmutable('now', new DateTimeZone('Europe/Berlin')))->format(DateTimeInterface::ATOM);
+    $ip   = $_SERVER['REMOTE_ADDR'] ?? '-';
+    $ua   = $_SERVER['HTTP_USER_AGENT'] ?? '-';
+    $line = $ts . ';' . $username . ';' . $ip . ';' . str_replace("\n", ' ', $ua) . "\n";
+    @file_put_contents(SW_MANUAL_LOG_FILE, $line, FILE_APPEND | LOCK_EX);
+}
+
+function sw_last_login_for_user(string $username): ?DateTimeImmutable {
+    if (!file_exists(SW_MANUAL_LOG_FILE)) {
+        return null;
+    }
+
+    $fh = @fopen(SW_MANUAL_LOG_FILE, 'r');
+    if (!$fh) {
+        return null;
+    }
+
+    $last = null;
+    while (($line = fgets($fh)) !== false) {
+        $parts = explode(';', trim($line));
+        if (count($parts) < 2) {
+            continue;
+        }
+        [$ts, $user] = $parts;
+        if ($user !== $username) {
+            continue;
+        }
+        try {
+            $dt = new DateTimeImmutable($ts);
+            if ($last === null || $dt > $last) {
+                $last = $dt;
+            }
+        } catch (Exception $e) {
+            continue;
+        }
+    }
+    fclose($fh);
+
+    return $last;
+}
+
+function sw_format_dt(?DateTimeImmutable $dt): string {
+    if ($dt === null) {
+        return '–';
+    }
+    return $dt->setTimezone(new DateTimeZone('Europe/Berlin'))->format('d.m.Y, H:i \U\h\r');
+}