supplycommit: add DefaultCommitConfTarget constant

Introduces `DefaultCommitConfTarget`, a constant for the default
confirmation target (in blocks) for a supply commitment transaction.

This constant provides a sensible default for fee estimation, ensuring
that the commitment transaction is confirmed in a timely manner without
overpaying. Centralizing this value makes it easier to manage and adjust
in the future.

If we don't set `CommitConfTarget` field in state machine env to a
reasonable value fee estimation will fail.

Author: ffranr

universe/supplycommit/env.go

@@ -20,6 +20,12 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 )
 
+const (
+	// DefaultCommitConfTarget is the default confirmation target used when
+	// crafting the commitment transaction. This is used in fee estimation.
+	DefaultCommitConfTarget = 6
+)
+
 // SupplySubTree is an enum that represents the different types of supply sub
 // trees within the main supply tree. The sub trees are used to track how the
 // supply shifts in response to: mints, burns, and ignores.

universe/supplycommit/state_machine_test.go

@@ -142,13 +142,14 @@ func newSupplyCommitTestHarness(t *testing.T,
 	mockErrReporter := &mockErrorReporter{}
 
 	env := &Environment{
-		AssetSpec:   cfg.assetSpec,
-		TreeView:    mockTreeView,
-		Commitments: mockCommits,
-		Wallet:      mockWallet,
-		KeyRing:     mockKey,
-		Chain:       mockChain,
-		StateLog:    mockStateLog,
+		AssetSpec:        cfg.assetSpec,
+		TreeView:         mockTreeView,
+		Commitments:      mockCommits,
+		Wallet:           mockWallet,
+		KeyRing:          mockKey,
+		Chain:            mockChain,
+		StateLog:         mockStateLog,
+		CommitConfTarget: DefaultCommitConfTarget,
 	}
 
 	fsmCfg := Config{