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>

web/css/components/app-tabs.css

@@ -1,9 +1,24 @@
+@layer components {
 .app-tabs {
   display: flex;
   flex-direction: column;
   gap: var(--app-spacing);
 }
 
+/* No-JS fallback: show only first tab panel. */
+html.no-js [data-tabs] [data-tab-panel] {
+  display: none;
+}
+
+html.no-js [data-tabs] [data-tab-panel]:first-of-type {
+  display: block;
+}
+
+/* JS mode: keep panels hidden until tab init completed (prevents flash). */
+html.js [data-tabs]:not([data-tabs-ready="1"]) [data-tab-panel] {
+  display: none !important;
+}
+
 .app-tabs-nav {
     display: flex;
     border-bottom: 1px solid var(--tabs-border);
@@ -42,6 +57,21 @@
   border-color: var(--tabs-active);
 }
 
+.app-tabs-nav button.has-invalid,
+.app-tabs-nav a.has-invalid {
+  color: var(--app-danger, #dc3545) !important;
+}
+
 [data-tab-panel][hidden] {
   display: none;
 }
+
+html.js [data-tabs][data-tabs-ready="1"] [data-tab-panel]:not([hidden]) {
+  display: block;
+}
+
+/* Safety fallback when JS is available but the ready marker is missing. */
+html:not(.no-js) [data-tabs] [data-tab-panel]:not([hidden]) {
+  display: block;
+}
+}