Generate a mailto link with subject and body (JSON body)

mailto: link with subject, cc, bcc and body. 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. Paid calls are counted as usage of the tool on yruz.one/toolkit. Price: 0.002 USDC per call.