lncfg: add new dev config option for scaling channel close confs

diff --git a/lncfg/dev.go b/lncfg/dev.go
index f048d69..8e0c9dd 100644
--- a/lncfg/dev.go
+++ b/lncfg/dev.go
@@ -5,6 +5,7 @@ package lncfg
 import (
 	"time"
 
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/lnwallet/chanfunding"
 )
 
@@ -58,3 +59,9 @@ func (d *DevConfig) GetMaxWaitNumBlocksFundingConf() uint32 {
 func (d *DevConfig) GetUnsafeConnect() bool {
 	return false
 }
+
+// ChannelCloseConfs returns the config value for channel close confirmations
+// override, which is always None for production build.
+func (d *DevConfig) ChannelCloseConfs() fn.Option[uint32] {
+	return fn.None[uint32]()
+}
diff --git a/lncfg/dev_integration.go b/lncfg/dev_integration.go
index 8ac85f5..b299fb4 100644
--- a/lncfg/dev_integration.go
+++ b/lncfg/dev_integration.go
@@ -5,6 +5,7 @@ package lncfg
 import (
 	"time"
 
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/lnwallet/chanfunding"
 )
 
@@ -27,6 +28,7 @@ type DevConfig struct {
 	UnsafeDisconnect            bool          `long:"unsafedisconnect" description:"Allows the rpcserver to intentionally disconnect from peers with open channels."`
 	MaxWaitNumBlocksFundingConf uint32        `long:"maxwaitnumblocksfundingconf" description:"Maximum blocks to wait for funding confirmation before discarding non-initiated channels."`
 	UnsafeConnect               bool          `long:"unsafeconnect" description:"Allow the rpcserver to connect to a peer even if there's already a connection."`
+	ForceChannelCloseConfs      uint32        `long:"force-channel-close-confs" description:"Force a specific number of confirmations for channel closes (dev/test only)"`
 }
 
 // ChannelReadyWait returns the config value `ProcessChannelReadyWait`.
@@ -71,3 +73,13 @@ func (d *DevConfig) GetMaxWaitNumBlocksFundingConf() uint32 {
 func (d *DevConfig) GetUnsafeConnect() bool {
 	return d.UnsafeConnect
 }
+
+// ChannelCloseConfs returns the forced confirmation count if set, or None if
+// the default behavior should be used.
+func (d *DevConfig) ChannelCloseConfs() fn.Option[uint32] {
+	if d.ForceChannelCloseConfs == 0 {
+		return fn.None[uint32]()
+	}
+
+	return fn.Some(d.ForceChannelCloseConfs)
+}