fix: use production mode for Enable Banking bank selector

BankSelector defaulted to sandbox=true. Now reads
NEXT_PUBLIC_ENABLE_BANKING_SANDBOX env var, defaulting to false
(production mode) when not set.

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

extensions/general/enable-banking/components/BankSelector.tsx

@@ -26,7 +26,7 @@ export function BankSelector({
   isLoading = false,
   className,
   country = 'SE',
-  sandbox = true, // Default to sandbox for development
+  sandbox = process.env.NEXT_PUBLIC_ENABLE_BANKING_SANDBOX === 'true',
 }: BankSelectorProps) {
   const widgetRef = useRef<HTMLElement | null>(null)
   const [scriptReady, setScriptReady] = useState(false)