add composer-unused, comprehensive docs, and project restructure

- Add icanhazstring/composer-unused as dev dependency for dependency hygiene checks
- Add German documentation (docs/) covering architecture, conventions, workflows, and developer checklists
- Add API layer (ApiAuth, ApiBootstrap, ApiResponse), audit, scheduler, custom fields, and SSO services
- Add Microsoft OIDC SSO, API token management, and user lifecycle features
- Add swagger-ui vendor integration and OpenAPI spec
- Add production Docker setup and bin/ scripts
- Update composer dependencies, config, templates, and frontend assets throughout

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pages/admin/docs/index($slug).php

@@ -0,0 +1,58 @@
+<?php
+
+use MintyPHP\Buffer;
+use MintyPHP\Http\Request;
+use MintyPHP\Router;
+use MintyPHP\Service\Access\PermissionService;
+use MintyPHP\Service\Docs\DocsCatalogService;
+use MintyPHP\Support\Guard;
+
+Guard::requireLogin();
+Guard::requirePermission(PermissionService::DOCS_VIEW);
+
+$docGroups = DocsCatalogService::docGroups();
+$allDocs = DocsCatalogService::allDocs();
+if ($allDocs === []) {
+    Router::redirect('error/not_found?url=' . urlencode(Request::pathWithQuery()));
+    return;
+}
+
+$slug = trim((string) ($slug ?? ''));
+if ($slug === '') {
+    Router::redirect('admin/docs/' . DocsCatalogService::defaultSlug());
+    return;
+}
+
+if (!array_key_exists($slug, $allDocs)) {
+    Router::redirect('error/not_found?url=' . urlencode(Request::pathWithQuery()));
+    return;
+}
+
+$rawMarkdown = DocsCatalogService::readMarkdown($slug);
+if ($rawMarkdown === null) {
+    Router::redirect('error/not_found?url=' . urlencode(Request::pathWithQuery()));
+    return;
+}
+
+$prepared = DocsCatalogService::prepareRenderedDocument($rawMarkdown, [1, 2, 3]);
+$renderedHtml = (string) ($prepared['html'] ?? '');
+$tocItems = [];
+foreach (($prepared['headings'] ?? []) as $heading) {
+    $level = (int) ($heading['level'] ?? 0);
+    if (!in_array($level, [2, 3], true)) {
+        continue;
+    }
+
+    $tocItems[] = [
+        'level' => $level,
+        'text' => (string) ($heading['text'] ?? ''),
+        'anchor' => (string) ($heading['anchor'] ?? ''),
+    ];
+}
+
+$currentSlug = $slug;
+$currentTitle = (string) ($allDocs[$slug] ?? $slug);
+
+Buffer::set('title', $currentTitle . ' - ' . t('Documentation'));
+Buffer::set('style_groups', json_encode(['docs']));
+Buffer::set('docs_rendered_html', $renderedHtml);

pages/admin/docs/index(default).phtml

@@ -0,0 +1,69 @@
+<?php
+
+/**
+ * @var string $renderedHtml       Rendered markdown HTML
+ * @var array<int, array<string, mixed>> $tocItems  TOC headings [{level, text, anchor}]
+ * @var array<string, array<string, string>> $docGroups  Grouped doc navigation
+ * @var string $currentSlug        Active slug
+ * @var string $currentTitle       Active doc title
+ */
+?>
+
+<div class="app-docs-container">
+
+    <aside class="app-docs-nav" aria-label="<?php e(t('Documentation navigation')); ?>">
+        <nav>
+            <?php foreach ($docGroups as $groupLabel => $items): ?>
+                <div class="app-docs-nav-group">
+                    <small class="muted"><?php e($groupLabel); ?></small>
+                    <ul>
+                        <?php foreach ($items as $docSlug => $label): ?>
+                            <?php $isActive = $docSlug === $currentSlug; ?>
+                            <li>
+                                <a href="<?php e(lurl('admin/docs/' . $docSlug)); ?>"
+                                    class="<?php e($isActive ? 'active' : ''); ?>"
+                                    <?php if ($isActive): ?>aria-current="page" <?php endif; ?>>
+                                    <?php e($label); ?>
+                                </a>
+                            </li>
+                        <?php endforeach; ?>
+                    </ul>
+                </div>
+            <?php endforeach; ?>
+        </nav>
+    </aside>
+
+    <article class="app-docs-content">
+        <?php
+        $breadcrumbs = [
+            ['label' => t('Home'), 'path' => 'admin'],
+            ['label' => t('Documentation'), 'path' => 'admin/docs/erste-schritte'],
+            ['label' => $currentTitle],
+        ];
+        require templatePath('partials/app-breadcrumb.phtml');
+        ?>
+        <?php MintyPHP\Buffer::get('docs_rendered_html'); ?>
+    </article>
+
+    <?php if ($tocItems): ?>
+        <aside class="app-docs-toc" aria-label="<?php e(t('On this page')); ?>">
+            <small class="muted"><?php e(t('On this page')); ?></small>
+            <ul>
+                <?php foreach ($tocItems as $item): ?>
+                    <li class="app-docs-toc-level-<?php e((string) $item['level']); ?>">
+                        <a href="<?php e(lurl('admin/docs/' . $currentSlug) . '#' . $item['anchor']); ?>"><?php e($item['text']); ?></a>
+                    </li>
+                <?php endforeach; ?>
+            </ul>
+        </aside>
+    <?php endif; ?>
+
+</div>
+
+<script>
+  window.addEventListener('DOMContentLoaded', function () {
+    document.querySelectorAll('.app-docs-content li > input[type="checkbox"][disabled]').forEach(function (checkbox) {
+      checkbox.removeAttribute('disabled');
+    });
+  });
+</script>