models: simplify models.Node

diff --git a/autopilot/prefattach_test.go b/autopilot/prefattach_test.go
index 70f7e2b..d93cda2 100644
--- a/autopilot/prefattach_test.go
+++ b/autopilot/prefattach_test.go
@@ -429,7 +429,10 @@ func (d *testDBGraph) addRandChannel(node1, node2 *btcec.PublicKey,
 					),
 					AuthSigBytes: testSig.Serialize(),
 				}
-				graphNode.AddPubKey(pub)
+				copy(
+					graphNode.PubKeyBytes[:],
+					pub.SerializeCompressed(),
+				)
 				err := d.db.AddNode(
 					context.Background(), graphNode,
 				)
@@ -459,7 +462,7 @@ func (d *testDBGraph) addRandChannel(node1, node2 *btcec.PublicKey,
 			),
 			AuthSigBytes: testSig.Serialize(),
 		}
-		dbNode.AddPubKey(nodeKey)
+		copy(dbNode.PubKeyBytes[:], nodeKey.SerializeCompressed())
 		if err := d.db.AddNode(
 			context.Background(), dbNode,
 		); err != nil {
@@ -560,7 +563,7 @@ func (d *testDBGraph) addRandNode() (*btcec.PublicKey, error) {
 		),
 		AuthSigBytes: testSig.Serialize(),
 	}
-	dbNode.AddPubKey(nodeKey)
+	copy(dbNode.PubKeyBytes[:], nodeKey.SerializeCompressed())
 	err = d.db.AddNode(context.Background(), dbNode)
 	if err != nil {
 		return nil, err
diff --git a/graph/db/models/node.go b/graph/db/models/node.go
index 23d6a42..d67aa4b 100644
--- a/graph/db/models/node.go
+++ b/graph/db/models/node.go
@@ -7,7 +7,6 @@ import (
 	"time"
 
 	"github.com/btcsuite/btcd/btcec/v2"
-	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
 	"github.com/lightningnetwork/lnd/lnwire"
 )
 
@@ -53,11 +52,6 @@ type Node struct {
 	// and ensure we're able to make upgrades to the network in a forwards
 	// compatible manner.
 	ExtraOpaqueData []byte
-
-	// TODO(roasbeef): discovery will need storage to keep it's last IP
-	// address and re-announce if interface changes?
-
-	// TODO(roasbeef): add update method and fetch?
 }
 
 // PubKey is the node's long-term identity public key. This key will be used to
@@ -79,22 +73,6 @@ func (l *Node) PubKey() (*btcec.PublicKey, error) {
 	return key, nil
 }
 
-// AuthSig is a signature under the advertised public key which serves to
-// authenticate the attributes announced by this node.
-//
-// NOTE: By having this method to access an attribute, we ensure we only need
-// to fully deserialize the signature if absolutely necessary.
-func (l *Node) AuthSig() (*ecdsa.Signature, error) {
-	return ecdsa.ParseSignature(l.AuthSigBytes)
-}
-
-// AddPubKey is a setter-link method that can be used to swap out the public
-// key for a node.
-func (l *Node) AddPubKey(key *btcec.PublicKey) {
-	l.pubKey = key
-	copy(l.PubKeyBytes[:], key.SerializeCompressed())
-}
-
 // NodeAnnouncement retrieves the latest node announcement of the node.
 func (l *Node) NodeAnnouncement(signed bool) (*lnwire.NodeAnnouncement1,
 	error) {
diff --git a/routing/pathfind_test.go b/routing/pathfind_test.go
index 77bad02..4414aa1 100644
--- a/routing/pathfind_test.go
+++ b/routing/pathfind_test.go
@@ -1250,11 +1250,9 @@ func runPathFindingWithAdditionalEdges(t *testing.T, useCache bool) {
 	dogePubKeyHex := "03dd46ff29a6941b4a2607525b043ec9b020b3f318a1bf281536fd7011ec59c882"
 	dogePubKeyBytes, err := hex.DecodeString(dogePubKeyHex)
 	require.NoError(t, err, "unable to decode public key")
-	dogePubKey, err := btcec.ParsePubKey(dogePubKeyBytes)
-	require.NoError(t, err, "unable to parse public key from bytes")
 
 	doge := &models.Node{}
-	doge.AddPubKey(dogePubKey)
+	copy(doge.PubKeyBytes[:], dogePubKeyBytes[:])
 	doge.Alias = "doge"
 	copy(doge.PubKeyBytes[:], dogePubKeyBytes)
 	graph.aliasMap["doge"] = doge.PubKeyBytes
diff --git a/routing/payment_session_source.go b/routing/payment_session_source.go
index bc1088d..1582005 100644
--- a/routing/payment_session_source.go
+++ b/routing/payment_session_source.go
@@ -1,7 +1,6 @@
 package routing
 
 import (
-	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/graph/db/models"
 	"github.com/lightningnetwork/lnd/htlcswitch"
@@ -102,17 +101,13 @@ func RouteHintsToEdges(routeHints [][]zpay32.HopHint, target route.Vertex) (
 			// we'll need to look at the next hint's start node. If
 			// we've reached the end of the hints list, we can
 			// assume we've reached the destination.
-			endNode := &models.Node{}
+			endNode := target
 			if i != len(routeHint)-1 {
-				endNode.AddPubKey(routeHint[i+1].NodeID)
-			} else {
-				targetPubKey, err := btcec.ParsePubKey(
-					target[:],
+				nodeID := routeHint[i+1].NodeID
+				copy(
+					endNode[:],
+					nodeID.SerializeCompressed(),
 				)
-				if err != nil {
-					return nil, err
-				}
-				endNode.AddPubKey(targetPubKey)
 			}
 
 			// Finally, create the channel edge from the hop hint
@@ -120,7 +115,7 @@ func RouteHintsToEdges(routeHints [][]zpay32.HopHint, target route.Vertex) (
 			// at the start of the channel.
 			edgePolicy := &models.CachedEdgePolicy{
 				ToNodePubKey: func() route.Vertex {
-					return endNode.PubKeyBytes
+					return endNode
 				},
 				ToNodeFeatures: lnwire.EmptyFeatureVector(),
 				ChannelID:      hopHint.ChannelID,