contractcourt: persist remote outgoing htlc claim outcome on disk

When a remote peer claims one of our outgoing htlcs on chain, we do
not care whether they claimed with multiple stages. We simply store
the claim outgome then forget the resolver.

contractcourt/htlc_timeout_resolver.go

@@ -6,6 +6,7 @@ import (
 	"io"
 
 	"github.com/btcsuite/btcd/wire"
+	"github.com/btcsuite/btcutil"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
@@ -157,7 +158,19 @@ func (h *htlcTimeoutResolver) claimCleanUp(
 		return nil, err
 	}
 	h.resolved = true
-	return nil, h.Checkpoint(h)
+
+	// Checkpoint our resolver with a report which reflects the preimage
+	// claim by the remote party.
+	amt := btcutil.Amount(h.htlcResolution.SweepSignDesc.Output.Value)
+	report := &channeldb.ResolverReport{
+		OutPoint:        h.htlcResolution.ClaimOutpoint,
+		Amount:          amt,
+		ResolverType:    channeldb.ResolverTypeOutgoingHtlc,
+		ResolverOutcome: channeldb.ResolverOutcomeClaimed,
+		SpendTxID:       commitSpend.SpenderTxHash,
+	}
+
+	return nil, h.Checkpoint(h, report)
 }
 
 // chainDetailsToWatch returns the output and script which we use to watch for