Validate and pretty-print a JSON document (JSON body)

Validate JSON and return it pretty-printed and minified, with type, depth and key count. No account or API key. Without PAYMENT-SIGNATURE the response is HTTP 402 with an x402 v2 payment challenge; pay and resend the identical request. Input as query string (GET) or JSON body (POST), max 64 KB; the payment is bound to the exact input. Price: 0.002 USDC per call.