build: adopt focused golangci-lint v2.13 checks

### .golangci.yml
@@ -69,6 +69,12 @@ linters:
     # have no context to thread through, so it adds little value for now.
     - noctx
 
+    # canonicalheader prefers registered initialism spellings such as
+    # Sec-WebSocket-Protocol, which can differ from the keys produced by
+    # net/http.CanonicalHeaderKey. Using those spellings as direct http.Header
+    # map keys can therefore break lookups.
+    - canonicalheader
+
     # Disable whitespace linters as it has conflict rules against our
     # contribution guidelines.
     - wsl
@@ -126,7 +132,8 @@ linters:
     # unit tests become our CI bottleneck.
     - paralleltest
 
-    # New linters that we haven't had time to address yet.
+    # New linters and expanded checks that we haven't had time to address yet.
+    - modernize
     - testifylint
     - perfsprint
     - inamedparam

### chanstate/kv_open_channel.go
@@ -52,8 +52,8 @@ func FetchChannelDataLossCommitPoint(
 }
 
 const (
-	// A tlv type definition used to serialize an outpoint's IndexStatus
-	// for use in the outpoint index.
+	// IndexStatusType is a TLV type definition used to serialize an
+	// outpoint's IndexStatus for use in the outpoint index.
 	IndexStatusType tlv.Type = 0
 )
 

### contractcourt/chain_arbitrator.go
@@ -1343,7 +1343,7 @@ func (c *ChainArbitrator) FindOutgoingHTLCDeadline(scid lnwire.ShortChannelID,
 // TODO(roasbeef): arbitration reports
 //  * types: contested, waiting for success conf, etc
 
-// NOTE: part of the `chainio.Consumer` interface.
+// Name returns the name of the chain arbitrator consumer.
 func (c *ChainArbitrator) Name() string {
 	return "ChainArbitrator"
 }

### lntest/harness.go
@@ -781,8 +781,8 @@ func (h *HarnessTest) NewNodeWatchOnly(name string, extraArgs []string,
 	return hn
 }
 
-// CreateNodeWatchOnly creates a new node and asserts its creation. The function
-// will only create the node and will not start it.
+// CreateNewNode creates a new node and asserts its creation. The function will
+// only create the node and will not start it.
 func (h *HarnessTest) CreateNewNode(name string, extraArgs []string,
 	password []byte, noAuth bool) *node.HarnessNode {
 
@@ -2370,7 +2370,8 @@ func (h *HarnessTest) SendCoins(a, b *node.HarnessNode,
 	return tx
 }
 
-// SendCoins sends all coins from node A to node B, returns the sending tx.
+// SendAllCoins sends all coins from node A to node B and returns the sending
+// transaction.
 func (h *HarnessTest) SendAllCoins(a, b *node.HarnessNode) *wire.MsgTx {
 	// Create an address for Bob receive the coins.
 	req := &lnrpc.NewAddressRequest{

### lntest/harness_assertion.go
@@ -2011,8 +2011,8 @@ func (h *HarnessTest) AssertChannelInGraphCache(hn *node.HarnessNode,
 	return edge
 }
 
-// AssertChannelInGraphDB asserts that a given channel is found both in the
-// graph db (GetChanInfo) and the graph cache (DescribeGraph).
+// AssertChannelInGraph asserts that a given channel is found both in the graph
+// db (GetChanInfo) and the graph cache (DescribeGraph).
 func (h *HarnessTest) AssertChannelInGraph(hn *node.HarnessNode,
 	chanPoint *lnrpc.ChannelPoint) *lnrpc.ChannelEdge {
 
@@ -2947,8 +2947,8 @@ func (h *HarnessTest) AssertForceCloseAndAnchorTxnsInMempool() (*wire.MsgTx,
 	}
 }
 
-// ReceiveSendToRouteUpdate waits until a message is received on the
-// PeerEventsClient stream or the timeout is reached.
+// ReceivePeerEvent waits until a message is received on the PeerEventsClient
+// stream or the timeout is reached.
 func (h *HarnessTest) ReceivePeerEvent(
 	stream rpc.PeerEventsClient) (*lnrpc.PeerEvent, error) {
 

### lntest/node/config.go
@@ -73,7 +73,7 @@ var (
 		"--protocol.simple-taproot-chans",
 	}
 
-	// CfgRbfCoopClose specifies the config used to create a node that
+	// CfgRbfClose specifies the config used to create a node that
 	// supports the new RBF close protocol.
 	CfgRbfClose = []string{
 		"--protocol.rbf-coop-close",

### lnwallet/chancloser/rbf_coop_transitions.go
@@ -25,7 +25,7 @@ import (
 )
 
 var (
-	// ErrInvalidStateTransition is returned if the remote party tries to
+	// ErrThawHeightNotReached is returned if the remote party tries to
 	// close, but the thaw height hasn't been matched yet.
 	ErrThawHeightNotReached = fmt.Errorf("thaw height not reached")
 )

### record/blinded_data.go
@@ -93,8 +93,8 @@ func NewNonFinalBlindedRouteData(chanID lnwire.ShortChannelID,
 	return info
 }
 
-// NewNonFinalBlindedRouteData creates the data that's provided for hops within
-// a blinded route.
+// NewNonFinalBlindedRouteDataOnionMessage creates the data that's provided for
+// hops within a blinded route.
 func NewNonFinalBlindedRouteDataOnionMessage(
 	nextNode fn.Either[*btcec.PublicKey, lnwire.ShortChannelID],
 	blindingOverride *btcec.PublicKey,

### sweep/fee_bumper.go
@@ -474,7 +474,7 @@ func (t *TxPublisher) updateRecord(r *monitorRecord,
 	return r
 }
 
-// NOTE: part of the `chainio.Consumer` interface.
+// Name returns the name of the transaction publisher consumer.
 func (t *TxPublisher) Name() string {
 	return "TxPublisher"
 }

### sweep/sweeper.go
@@ -506,7 +506,7 @@ func (s *UtxoSweeper) Stop() error {
 	return nil
 }
 
-// NOTE: part of the `chainio.Consumer` interface.
+// Name returns the name of the UTXO sweeper consumer.
 func (s *UtxoSweeper) Name() string {
 	return "UtxoSweeper"
 }

### zpay32/decode.go
@@ -32,8 +32,8 @@ var (
 	// not valid UTF-8.
 	ErrInvalidUTF8Description = errors.New("description is not valid UTF-8")
 
-	// ErrLengthNotMultipleOfHopHintLength is returned if the length of the
-	// route hint data is not a multiple of the hop hint length.
+	// ErrLengthNotMultipleOfHopHint is returned if the length of the route
+	// hint data is not a multiple of the hop hint length.
 	ErrLengthNotMultipleOfHopHint = errors.New("length is not a multiple " +
 		"of hop hint length")