feat(i18n): add re-edit @mention keys (edit/editing-announce/dismiss)

Keys for the re-edit affordance landing in #628:
- person_mention_edit_label   — pencil button aria-label
- person_mention_editing_announce — aria-live editing context
- person_mention_dismiss_label — dropdown close button aria-label

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/messages/de.json

@@ -506,6 +506,9 @@
 	"person_mention_create_new": "Neue Person anlegen",
 	"person_mention_results_count_singular": "1 Person gefunden",
 	"person_mention_results_count_plural": "{count} Personen gefunden",
+	"person_mention_edit_label": "Erwähnung bearbeiten",
+	"person_mention_editing_announce": "Erwähnung wird bearbeitet: {displayName}",
+	"person_mention_dismiss_label": "Suche schließen",
 	"transcription_editor_aria_label": "Transkriptionstext",
 	"person_born_name_prefix": "geb.",
 	"page_title_home": "Archiv",

frontend/messages/en.json

@@ -506,6 +506,9 @@
 	"person_mention_create_new": "Create new person",
 	"person_mention_results_count_singular": "1 person found",
 	"person_mention_results_count_plural": "{count} persons found",
+	"person_mention_edit_label": "Edit mention",
+	"person_mention_editing_announce": "Editing mention: {displayName}",
+	"person_mention_dismiss_label": "Close search",
 	"transcription_editor_aria_label": "Transcription text",
 	"person_born_name_prefix": "née",
 	"page_title_home": "Archive",

frontend/messages/es.json

@@ -506,6 +506,9 @@
 	"person_mention_create_new": "Crear nueva persona",
 	"person_mention_results_count_singular": "1 persona encontrada",
 	"person_mention_results_count_plural": "{count} personas encontradas",
+	"person_mention_edit_label": "Editar mención",
+	"person_mention_editing_announce": "Editando mención: {displayName}",
+	"person_mention_dismiss_label": "Cerrar búsqueda",
 	"transcription_editor_aria_label": "Texto de transcripción",
 	"person_born_name_prefix": "n.",
 	"page_title_home": "Archivo",