4.10 reconstruction: BTL4OPT.EXE links clean and BOOTS to the first staged brick

The reconstructed tree now produces a runnable binary with the authentic
1995 toolchain (BC4.52 / tlink32 / DPMI32):

- BTL4.CPP main TU reconstructed from the 4.11 Ghidra decomp (FUN_0040109c)
  + the 4.10 binary's own string pool + surviving RPL4TOOL.CPP house style;
  probe_main.cpp scaffold retired (BTL4.NOTES.md documents every decoded call)
- L4NET.CPP staged: L4NetworkManager ctor/dtor + 10 vtable-pulled virtuals
  (standalone-benign ones no-op, network ones Fail loudly) + NetNub client
  globals (Net_Common_Ptr=NULL routes L4File to its plain-DOS path)
- build410.sh: libs now built in the AUTHENTIC makefile member order
  (MUNGA.MAK / mungal4.mak / BT.MAK / BTL4.MAK). Order is load-bearing:
  tlink emits static-init records in module pull order, and alphabetical
  order booted into a null-vptr crash (IcomManager::ClassDerivations
  constructing before parent NetworkClient::ClassDerivations). Also fixed
  stage_link to the proven 32-bit lib set (SOSDBXC+SOSMBXC, no WATTCPLG)
- BOXTREE.HPP MemoryBlock unify, BTL4GRND notify stubs, remaining engine
  backfills (audio/gauge/resource/stream TUs) that closed the deep ledger

Smoke test (DOSBox-X + 32RTM, copy of the pod BT tree, our exe swapped in):
  BattleTech v4.10
  BTL4Application::BTL4Application
  l4net.cpp(22): L4NetworkManager -- l4net.cpp not yet reconstructed
Static init, main, -egg parse, BTL4.RES load (version 1.0.6 check passes),
ApplicationManager and the BTL4Application ctor chain all execute real
reconstructed code; boot halts at the first staged Fail() as designed.
Next brick: the real l4net.cpp body.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

restoration/source410/MUNGA_L4/L4NET.CPP

@@ -0,0 +1,119 @@
+//===========================================================================//
+// File:	l4net.cpp                                                           //
+// Project: MUNGA           Brick: L4 Network                                 //
+// Contents: Implementation details for the L4 network manager               //
+//---------------------------------------------------------------------------//
+// Copyright (C) 1994-1995, Virtual World Entertainment, Inc.                //
+// All Rights reserved worldwide                                             //
+// This unpublished sourcecode is PROPRIETARY and CONFIDENTIAL               //
+//===========================================================================//
+
+#include <mungal4.hpp>
+#pragma hdrstop
+
+#if !defined(L4NET_HPP)
+#	include <l4net.hpp>
+#endif
+
+L4NetworkManager::L4NetworkManager():
+	NetworkManager(NetworkManager::DefaultData),
+	messageBuffer(this)
+{
+	Fail("L4NetworkManager -- l4net.cpp not yet reconstructed");
+}
+
+void
+	L4NetworkManager::CreateConsoleHost()
+{
+	Fail("L4NetworkManager::CreateConsoleHost -- l4net.cpp not yet reconstructed");
+}
+
+L4NetworkManager__MessageBuffer::L4NetworkManager__MessageBuffer(L4NetworkManager *network_manager):
+	messageQueueSocket(NULL, 1)
+{
+	networkManager = network_manager;
+	bufferSize = 0;
+}
+
+L4NetworkManager__MessageBuffer::~L4NetworkManager__MessageBuffer()
+{
+}
+
+//
+//#############################################################################
+// Staged bodies: real l4net.cpp not yet reconstructed.  Methods that a
+// standalone (non-networked) boot may touch are benign no-ops; methods that
+// imply real network traffic Fail loudly.
+//#############################################################################
+//
+L4NetworkManager::~L4NetworkManager()
+{
+}
+
+void
+	L4NetworkManager::Send(Message *, ClientID, HostID)
+{
+	Fail("L4NetworkManager::Send -- l4net.cpp not yet reconstructed");
+}
+
+void
+	L4NetworkManager::ExclusiveBroadcast(Message *, ClientID)
+{
+	Fail("L4NetworkManager::ExclusiveBroadcast -- l4net.cpp not yet reconstructed");
+}
+
+void
+	L4NetworkManager::StartConnecting(Mission *)
+{
+	Fail("L4NetworkManager::StartConnecting -- l4net.cpp not yet reconstructed");
+}
+
+Logical
+	L4NetworkManager::Shutdown()
+{
+	return 1;
+}
+
+Logical
+	L4NetworkManager::CheckBuffers(NetworkPacket *)
+{
+	Fail("L4NetworkManager::CheckBuffers -- l4net.cpp not yet reconstructed");
+	return 0;
+}
+
+void
+	L4NetworkManager::RemovePacket(NetworkPacket *)
+{
+	Fail("L4NetworkManager::RemovePacket -- l4net.cpp not yet reconstructed");
+}
+
+Logical
+	L4NetworkManager::ExecuteBackground()
+{
+	return 0;
+}
+
+void
+	L4NetworkManager::Marker(char *)
+{
+}
+
+void
+	L4NetworkManager::Mode(NetworkMode)
+{
+}
+
+//
+//#############################################################################
+// NetNub client-side globals (real home: l4net.cpp).  Net_Common_Ptr NULL =
+// no NetNub TSR loaded; L4File then takes its plain-DOS path (L4FILE.CPP:32).
+//#############################################################################
+//
+Netcom_Ptr
+	Net_Common_Ptr = NULL;
+
+void
+	NetNub::SendCommand()
+{
+	Fail("NetNub::SendCommand -- l4net.cpp not yet reconstructed");
+}