multi: add and use V1 constructor for models.ChannelEdgeInfo

This makes it clear what fields must/can be set for a V1 channel.

Introduce NewV1Channel constructor to create v1 channel edges with
proper initialization and validation. The constructor:

- Takes required fields (chanID, chainHash, node keys) as parameters
- Takes v1-specific fields (bitcoin keys, extra opaque data) via
  ChannelV1Fields struct
- Accepts optional fields (capacity, channel point, features, proof)
  via functional options (WithCapacity, WithChannelPoint, etc.)
- Validates that if an AuthProof is provided, its version matches the
  channel version

This makes it clear which fields are required vs optional for v1
channels and prevents incorrectly initialized channel edges. All
tests and production code updated to use the constructor.

routing/pathfind_test.go

@@ -19,6 +19,7 @@ import (
 	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
 	"github.com/btcsuite/btcd/btcutil"
+	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	sphinx "github.com/lightningnetwork/lightning-onion"
@@ -345,19 +346,28 @@ func parseTestGraph(t *testing.T, useCache bool, path string) (
 
 		// We first insert the existence of the edge between the two
 		// nodes.
-		edgeInfo := models.ChannelEdgeInfo{
-			Version:      lnwire.GossipVersion1,
-			ChannelID:    edge.ChannelID,
-			AuthProof:    &testAuthProof,
-			ChannelPoint: fundingPoint,
-			Features:     lnwire.EmptyFeatureVector(),
-			Capacity:     btcutil.Amount(edge.Capacity),
-		}
+		var node1Vertex, node2Vertex route.Vertex
+		copy(node1Vertex[:], node1Bytes)
+		copy(node2Vertex[:], node2Bytes)
 
-		copy(edgeInfo.NodeKey1Bytes[:], node1Bytes)
-		copy(edgeInfo.NodeKey2Bytes[:], node2Bytes)
-		copy(edgeInfo.BitcoinKey1Bytes[:], node1Bytes)
-		copy(edgeInfo.BitcoinKey2Bytes[:], node2Bytes)
+		var btcKey1, btcKey2 route.Vertex
+		copy(btcKey1[:], node1Bytes)
+		copy(btcKey2[:], node2Bytes)
+
+		edgeInfo, err := models.NewV1Channel(
+			edge.ChannelID, *chaincfg.SimNetParams.GenesisHash,
+			node1Vertex, node2Vertex,
+			&models.ChannelV1Fields{
+				BitcoinKey1Bytes: btcKey1,
+				BitcoinKey2Bytes: btcKey2,
+			},
+			models.WithChanProof(&testAuthProof),
+			models.WithChannelPoint(fundingPoint),
+			models.WithCapacity(btcutil.Amount(edge.Capacity)),
+		)
+		if err != nil {
+			return nil, err
+		}
 
 		shortID := lnwire.NewShortChanIDFromInt(edge.ChannelID)
 		links[shortID] = &mockLink{
@@ -366,7 +376,7 @@ func parseTestGraph(t *testing.T, useCache bool, path string) (
 			),
 		}
 
-		err = graph.AddChannelEdge(ctx, &edgeInfo)
+		err = graph.AddChannelEdge(ctx, edgeInfo)
 		if err != nil && !errors.Is(err, graphdb.ErrEdgeAlreadyExist) {
 			return nil, err
 		}
@@ -396,12 +406,12 @@ func parseTestGraph(t *testing.T, useCache bool, path string) (
 		}
 
 		// We also store the channel IDs info for each of the node.
-		node1Vertex, err := route.NewVertexFromBytes(node1Bytes)
+		node1Vertex, err = route.NewVertexFromBytes(node1Bytes)
 		if err != nil {
 			return nil, err
 		}
 
-		node2Vertex, err := route.NewVertexFromBytes(node2Bytes)
+		node2Vertex, err = route.NewVertexFromBytes(node2Bytes)
 		if err != nil {
 			return nil, err
 		}
@@ -678,21 +688,21 @@ func createTestGraphFromChannels(t *testing.T, useCache bool,
 
 		// We first insert the existence of the edge between the two
 		// nodes.
-		edgeInfo := models.ChannelEdgeInfo{
-			Version:      lnwire.GossipVersion1,
-			ChannelID:    channelID,
-			AuthProof:    &testAuthProof,
-			ChannelPoint: *fundingPoint,
-			Capacity:     testChannel.Capacity,
-			Features:     lnwire.EmptyFeatureVector(),
-
-			NodeKey1Bytes:    node1Vertex,
-			BitcoinKey1Bytes: node1Vertex,
-			NodeKey2Bytes:    node2Vertex,
-			BitcoinKey2Bytes: node2Vertex,
+		edgeInfo, err := models.NewV1Channel(
+			channelID, *chaincfg.SimNetParams.GenesisHash,
+			node1Vertex, node2Vertex, &models.ChannelV1Fields{
+				BitcoinKey1Bytes: node1Vertex,
+				BitcoinKey2Bytes: node2Vertex,
+			},
+			models.WithChanProof(&testAuthProof),
+			models.WithChannelPoint(*fundingPoint),
+			models.WithCapacity(testChannel.Capacity),
+		)
+		if err != nil {
+			return nil, err
 		}
 
-		err = graph.AddChannelEdge(ctx, &edgeInfo)
+		err = graph.AddChannelEdge(ctx, edgeInfo)
 		if err != nil && !errors.Is(err, graphdb.ErrEdgeAlreadyExist) {
 			return nil, err
 		}