chanmon_consistency: resync stale monitors to chain tip during settlement

After a node reload with an older monitor, the fuzzer's node_height
tracking variable stays at the pre-reload height. During settlement,
sync_with_chain_state starts from node_height, so it never re-delivers
the blocks that the stale monitor missed. If a commitment tx was
confirmed in one of those missed blocks, the monitor never learns about
the funding spend, causing get_claimable_balances() to incorrectly
report a ClaimableOnChannelClose balance.

Fix this by resetting each node_height to the minimum of its current
value and all its monitors' best_block heights at the start of
settlement, ensuring sync_with_chain_state re-delivers missed blocks.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: joostjager

fuzz/src/chanmon_consistency.rs

@@ -2875,6 +2875,23 @@ pub fn do_test<Out: Output + MaybeSend + MaybeSync>(
 				nodes[1].signer_unblocked(None);
 				nodes[2].signer_unblocked(None);
 
+				// After a node reload with an older monitor, node_height may be
+				// ahead of the monitor's best_block. Reset to the minimum so
+				// sync_with_chain_state re-delivers missed blocks during settlement.
+				for (node, monitor, node_height) in [
+					(&nodes[0], &monitor_a, &mut node_height_a),
+					(&nodes[1], &monitor_b, &mut node_height_b),
+					(&nodes[2], &monitor_c, &mut node_height_c),
+				] {
+					let mut min = std::cmp::min(*node_height, node.current_best_block().height);
+					for chan_id in monitor.chain_monitor.list_monitors() {
+						if let Ok(mon) = monitor.chain_monitor.get_monitor(chan_id) {
+							min = std::cmp::min(min, mon.current_best_block().height);
+						}
+					}
+					*node_height = min;
+				}
+
 				macro_rules! process_all_events {
 					() => { {
 						let mut last_pass_no_updates = false;