Decouple LSPS4 webhooks from liquidity loop

Send LSPS4 wake-up webhooks in the background instead of awaiting the
HTTP response on the liquidity event loop.

Direct webhook delivery was meant to reduce wake-up latency, but waiting
for the response made unrelated liquidity work depend on the client's
webhook handler. When that handler keeps the request open while the
node wakes and starts processing payments, follow-up actions such as
opening a channel can be delayed behind the webhook.

Keep a long timeout on the background request as cleanup for genuinely
stuck connections. The timeout is not part of LSPS4 control flow; it is
there to bound resource usage while still treating the webhook as
best-effort.

Author: amackillop

src/liquidity.rs

@@ -61,6 +61,10 @@ use crate::fee_estimator::{self, ConfirmationTarget, FeeEstimator, OnchainFeeEst
 use crate::{total_anchor_channels_reserve_sats, Config, Error};
 
 const LIQUIDITY_REQUEST_TIMEOUT_SECS: u64 = 5;
+// Client webhooks may intentionally keep the HTTP response open while the node wakes
+// and processes incoming payments. This timeout is only to clean up genuinely stuck
+// requests without blocking LSPS4 liquidity actions.
+const DIRECT_WEBHOOK_TIMEOUT_SECS: u64 = 70;
 
 const LSPS2_GETINFO_REQUEST_EXPIRY: Duration = Duration::from_secs(60 * 60 * 24);
 pub(crate) const LSPS2_CHANNEL_CLTV_EXPIRY_DELTA: u32 = 72;
@@ -1332,15 +1336,36 @@ where
 					let mut json_body = HashMap::new();
 					json_body.insert("nodeId", counterparty_node_id.to_string());
 					json_body.insert("paymentHash", payment_hash.to_string());
+					let counterparty_node_id = counterparty_node_id.to_string();
+					let payment_hash = payment_hash.to_string();
+					let client = client.clone();
+					let url = url.clone();
 					log_info!(
 						self.logger,
 						"Sending webhook directly for payment_hash={} node={}",
 						payment_hash,
 						counterparty_node_id
 					);
-					if let Err(e) = client.post(url).json(&json_body).send().await {
-						log_error!(self.logger, "Direct webhook POST failed: {:?}", e);
-					}
+					let _ = tokio::spawn(async move {
+						match tokio::time::timeout(
+							Duration::from_secs(DIRECT_WEBHOOK_TIMEOUT_SECS),
+							client.post(&url).json(&json_body).send(),
+						)
+						.await
+						{
+							Ok(Ok(_)) => {},
+							Ok(Err(e)) => {
+								log::error!("Direct webhook POST failed: {:?}", e);
+							},
+							Err(_) => {
+								log::error!(
+									"Direct webhook POST timed out for payment_hash={} node={}",
+									payment_hash,
+									counterparty_node_id
+								);
+							},
+						}
+					});
 				} else {
 					// Fallback: route through event queue (slower path via S3 persistence).
 					log_info!(