refactor(person): remove redundant conversations link from header

The co-correspondent chips already link directly to the conversation view
pre-filled with both persons, making the generic "Konversationen anzeigen"
header link redundant. Removed the link and the person_btn_conversations
i18n key from all three locales.

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

frontend/messages/es.json

@@ -189,5 +189,4 @@
 	"comp_taginput_placeholder_filter": "Filtrar por etiquetas...",
 	"comp_taginput_remove": "Eliminar etiqueta",
 	"comp_taginput_create_hint": "Pulse Enter para crear etiqueta.",
-	"person_btn_conversations": "Ver conversaciones"
 }