refactor: replace hardcoded aria-labels with i18n keys, add common.close/remove/home

js/components/error-boundary.js

@@ -37,10 +37,10 @@ class ErrorBoundary extends HTMLElement {
         this.innerHTML = /* html */`
             <div class="error-boundary">
                 <div class="error-icon">⚠️</div>
-                <h3 class="error-title">${t('error.title') || 'Etwas ist schiefgelaufen'}</h3>
+                <h3 class="error-title">${t('error.title')}</h3>
                 <p class="error-message">${escapeHTML(errorMessage)}</p>
                 <button class="btn btn-primary error-retry" type="button">
-                    ${t('error.retry') || 'Erneut versuchen'}
+                    ${t('error.retry')}
                 </button>
             </div>
         `
@@ -131,7 +131,7 @@ function showErrorToast(message) {
     toast.innerHTML = /* html */`
         <span class="error-toast-icon">⚠️</span>
         <span class="error-toast-message">${escapeHTML(message)}</span>
-        <button class="error-toast-close" aria-label="Schließen">×</button>
+        <button class="error-toast-close" aria-label="${t('common.close')}">×</button>
     `
 
     document.body.appendChild(toast)