feat(i18n): add search_chip_theme_prefix to de/en/es message bundles

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

frontend/messages/de.json

@@ -42,6 +42,7 @@
 	"search_chip_sender": "Absender",
 	"search_chip_date": "Zeitraum",
 	"search_chip_keyword": "Stichwort",
+	"search_chip_theme_prefix": "Thema",
 	"search_chip_directional_label": "Von {from} zu {to}, Filter entfernen",
 	"search_disambiguation_trigger_label": "Mehrere Personen gefunden — zum Auswählen klicken",
 	"search_disambiguation_cue": "(auswählen…)",

frontend/messages/en.json

@@ -42,6 +42,7 @@
 	"search_chip_sender": "Sender",
 	"search_chip_date": "Period",
 	"search_chip_keyword": "Keyword",
+	"search_chip_theme_prefix": "Topic",
 	"search_chip_directional_label": "From {from} to {to}, remove filter",
 	"search_disambiguation_trigger_label": "Several people found — click to choose",
 	"search_disambiguation_cue": "(choose…)",

frontend/messages/es.json

@@ -42,6 +42,7 @@
 	"search_chip_sender": "Remitente",
 	"search_chip_date": "Período",
 	"search_chip_keyword": "Palabra clave",
+	"search_chip_theme_prefix": "Tema",
 	"search_chip_directional_label": "De {from} a {to}, eliminar filtro",
 	"search_disambiguation_trigger_label": "Se encontraron varias personas — haga clic para elegir",
 	"search_disambiguation_cue": "(elegir…)",