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/api-docs/index().php

@@ -0,0 +1,11 @@
+<?php
+
+use MintyPHP\Buffer;
+use MintyPHP\Support\Guard;
+use MintyPHP\Service\Access\PermissionService;
+
+Guard::requireLogin();
+Guard::requirePermission(PermissionService::API_DOCS_VIEW);
+
+Buffer::set('title', t('API docs'));
+Buffer::set('style_groups', json_encode(['api-docs']));