pay_part_start -- Notification for xpay part start

DESCRIPTION

Notification added in v25.09.

The pay_part_start notification is emitted by the xpay plugin when a payment part begins.

payment_hash (hash): The payment hash for the xpay invocation.
groupid (u64): The xpay group identifier for the payment attempt.
partid (u64): The identifier for this payment part.
total_payment_msat (msat): The total payment amount for the xpay invocation.
attempt_msat (msat): The amount this payment part attempts to deliver.
hops (array of objects): The route hops for this payment part.:
- next_node (pubkey): The next node for this hop.
- short_channel_id (short_channel_id): The short channel id used for this hop.
- direction (u32): The direction within the short channel id.
- channel_in_msat (msat): The amount entering the hop.
- channel_out_msat (msat): The amount leaving the hop.