initial commit: standalone SoftEther VPN client in Go

Built-in DHCP (raw Ethernet frames through tunnel), automatic reconnection,
host route management, classless static routes (option 121/249), DNS config.
Single static binary, Linux only.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vendor/golang.org/x/sys/unix/bluetooth_linux.go

@@ -0,0 +1,36 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Bluetooth sockets and messages
+
+package unix
+
+// Bluetooth Protocols
+const (
+	BTPROTO_L2CAP  = 0
+	BTPROTO_HCI    = 1
+	BTPROTO_SCO    = 2
+	BTPROTO_RFCOMM = 3
+	BTPROTO_BNEP   = 4
+	BTPROTO_CMTP   = 5
+	BTPROTO_HIDP   = 6
+	BTPROTO_AVDTP  = 7
+)
+
+const (
+	HCI_CHANNEL_RAW     = 0
+	HCI_CHANNEL_USER    = 1
+	HCI_CHANNEL_MONITOR = 2
+	HCI_CHANNEL_CONTROL = 3
+	HCI_CHANNEL_LOGGING = 4
+)
+
+// Socketoption Level
+const (
+	SOL_BLUETOOTH = 0x112
+	SOL_HCI       = 0x0
+	SOL_L2CAP     = 0x6
+	SOL_RFCOMM    = 0x12
+	SOL_SCO       = 0x11
+)