Function validatePnStamp

validatePnStamp(
transientData: Uint8Array<ArrayBufferLike>,
targetCost: number,
): Promise<ValidatedPnStamp | null>
Validates a single propagation-node stamp from a received propagation blob (LXStamper.validate_pn_stamp). The blob is lxmf_data || stamp; the trailing STAMP_SIZE bytes are the stamp and transient_id is SHA-256 over the base lxmf_data (so it is stable across stamp changes).
Parameters
- transientData: Uint8Array<ArrayBufferLike>
  The propagation blob (lxmf_data + stamp).
- targetCost: number
  Minimum required stamp value (leading zero bits).
Returns Promise<ValidatedPnStamp | null>
null when the blob is too short or the stamp does not meet targetCost.
- Defined in packages/core/src/lxmf/stamper.js:203