fix(admin): add client-side search, pagination, toast feedback, confirm dialogs and test result display

- Rewrite manage/import/presets/test tabs as client component with sonner toasts
- Add client-side search filtering (no page reload)
- Add pagination (25 per page)
- Add confirm dialog before delete and clear-all
- Show test results inline after submission
- Add toast feedback for import, preset apply, save, delete
- Add prev/next pagination labels

src/messages/nl.json

@@ -2086,7 +2086,17 @@
 					"textColor": "Tekstkleur",
 					"rounded": "Afgeronde hoeken",
 					"save": "Opslaan als favicon"
-				}
+				},
+				"errorOccurred": "Er is een fout opgetreden",
+				"emptyInput": "Lege invoer",
+				"invalidJson": "Ongeldige JSON",
+				"imported": "Ge\u00efmporteerd!",
+				"cleared": "Alle permissies verwijderd!",
+				"invalidRank": "Ongeldige rang",
+				"testDone": "Test voltooid: {count} permissies gevonden",
+				"testing": "Testen...",
+				"prev": "Vorige",
+				"next": "Volgende"
 			},
 			"settings": {
 				"title": "CMS-instellingen",