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>

tests/Repository/RepoQueryTest.php

@@ -45,7 +45,7 @@ class RepoQueryTest extends TestCase
         $this->assertSame([], $params);
 
         RepoQuery::addLikeFilter($where, $params, ['a', 'b'], 'foo');
-        $this->assertSame(['(a like ? or b like ?)'], $where);
+        $this->assertSame(["(a like ? escape '\\\\' or b like ? escape '\\\\')"], $where);
         $this->assertSame(['%foo%', '%foo%'], $params);
     }