fix(stammbaum): state-aware aria-label on family-member toggle — WCAG accessible name

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

frontend/messages/de.json

@@ -965,6 +965,8 @@
 	"relation_year_to": "bis {year}",
 	"relation_year_error_bis_before_von": "Bis-Jahr darf nicht vor Von-Jahr liegen.",
 	"relation_label_family_member": "Als Familienmitglied",
+	"relation_toggle_add_to_tree": "Zum Stammbaum hinzufügen",
+	"relation_toggle_remove_from_tree": "Aus Stammbaum entfernen",
 	"relation_label_in_tree": "Erscheint im Stammbaum",
 	"relation_label_view_in_tree": "Ansehen →",
 	"relation_label_direct": "Direkte Beziehungen",

frontend/messages/en.json

@@ -965,6 +965,8 @@
 	"relation_year_to": "until {year}",
 	"relation_year_error_bis_before_von": "End year must not precede start year.",
 	"relation_label_family_member": "Family member",
+	"relation_toggle_add_to_tree": "Add to family tree",
+	"relation_toggle_remove_from_tree": "Remove from family tree",
 	"relation_label_in_tree": "Appears in the family tree",
 	"relation_label_view_in_tree": "View →",
 	"relation_label_direct": "Direct relationships",

frontend/messages/es.json

@@ -965,6 +965,8 @@
 	"relation_year_to": "hasta {year}",
 	"relation_year_error_bis_before_von": "El año final no puede ser anterior al año inicial.",
 	"relation_label_family_member": "Miembro de la familia",
+	"relation_toggle_add_to_tree": "Añadir al árbol genealógico",
+	"relation_toggle_remove_from_tree": "Quitar del árbol genealógico",
 	"relation_label_in_tree": "Aparece en el árbol genealógico",
 	"relation_label_view_in_tree": "Ver →",
 	"relation_label_direct": "Relaciones directas",