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.

autopilot/prefattach_test.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/btcutil"
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	graphdb "github.com/lightningnetwork/lnd/graph/db"
 	"github.com/lightningnetwork/lnd/graph/db/models"
 	"github.com/lightningnetwork/lnd/lnwire"
@@ -492,16 +493,20 @@ func (d *testDBGraph) addRandChannel(node1, node2 *btcec.PublicKey,
 	}
 
 	chanID := randChanID()
-	edge := &models.ChannelEdgeInfo{
-		Version:   lnwire.GossipVersion1,
-		ChannelID: chanID.ToUint64(),
-		Capacity:  capacity,
-		Features:  lnwire.EmptyFeatureVector(),
+	nodeKey1 := route.NewVertex(lnNode1)
+	nodeKey2 := route.NewVertex(lnNode2)
+	btcKey1 := route.NewVertex(lnNode1)
+	btcKey2 := route.NewVertex(lnNode2)
+	edge, err := models.NewV1Channel(
+		chanID.ToUint64(), chainhash.Hash{}, nodeKey1, nodeKey2,
+		&models.ChannelV1Fields{
+			BitcoinKey1Bytes: btcKey1,
+			BitcoinKey2Bytes: btcKey2,
+		}, models.WithCapacity(capacity),
+	)
+	if err != nil {
+		return nil, nil, err
 	}
-	copy(edge.NodeKey1Bytes[:], lnNode1.SerializeCompressed())
-	copy(edge.NodeKey2Bytes[:], lnNode2.SerializeCompressed())
-	copy(edge.BitcoinKey1Bytes[:], lnNode1.SerializeCompressed())
-	copy(edge.BitcoinKey2Bytes[:], lnNode2.SerializeCompressed())
 
 	if err := d.db.AddChannelEdge(ctx, edge); err != nil {
 		return nil, nil, err