feat(i18n): add themen widget and page translation keys

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

frontend/messages/de.json

@@ -1084,5 +1084,10 @@
 	"timeline_dragging_aria_live": "Zeitraum {from} bis {to} ausgewählt",
 	"error_page_id_label": "Fehler-ID",
 	"error_copy_id_label": "ID kopieren",
-	"error_copied": "Kopiert!"
+	"error_copied": "Kopiert!",
+	"themen_widget_title": "Themen",
+	"themen_alle": "Alle Themen",
+	"themen_leer": "Noch keine Themen vergeben.",
+	"themen_weitere": "+ {count} weitere",
+	"themen_dokumente": "{count} Dokumente"
 }

frontend/messages/en.json

@@ -1084,5 +1084,10 @@
 	"timeline_dragging_aria_live": "Range {from} to {to} selected",
 	"error_page_id_label": "Error ID",
 	"error_copy_id_label": "Copy ID",
-	"error_copied": "Copied!"
+	"error_copied": "Copied!",
+	"themen_widget_title": "Topics",
+	"themen_alle": "All Topics",
+	"themen_leer": "No topics assigned yet.",
+	"themen_weitere": "+ {count} more",
+	"themen_dokumente": "{count} documents"
 }

frontend/messages/es.json

@@ -1084,5 +1084,10 @@
 	"timeline_dragging_aria_live": "Rango {from} a {to} seleccionado",
 	"error_page_id_label": "ID de error",
 	"error_copy_id_label": "Copiar ID",
-	"error_copied": "¡Copiado!"
+	"error_copied": "¡Copiado!",
+	"themen_widget_title": "Temas",
+	"themen_alle": "Todos los temas",
+	"themen_leer": "Aún no hay temas.",
+	"themen_weitere": "+ {count} más",
+	"themen_dokumente": "{count} documentos"
 }