Export MultiplayerExt symbols accessed from isle executable (#1)

* Export MultiplayerExt symbols accessed from isle executable

When lego1 is built as a shared library (DLL), symbols used by the isle
executable through the Extension<T>::Call() template need to be exported.
Add LEGO1_EXPORT to MultiplayerExt::enabled and MultiplayerExt::CheckRejected()
which are referenced from isleapp.cpp via the template instantiation.

https://claude.ai/code/session_01HHMmowothg25fephi6iidq

* Use inline const instead of constexpr for extension function pointers

constexpr cannot be used with dllimport function addresses since they
are resolved at load time through the IAT, not at compile time. Change
to inline const which preserves the single-definition semantics (via
inline) while allowing runtime initialization of the function pointers.

https://claude.ai/code/session_01HHMmowothg25fephi6iidq

* Fix multiplayer extension link errors across DLL boundary

When lego1 is a shared library, Extension<T>::Call() instantiated from
isle.exe references MultiplayerExt::enabled and CheckRejected() which
are not exported. Instead of exporting internal symbols (which also
breaks constexpr with dllimport), add an exported IsMultiplayerRejected()
wrapper that keeps the Extension<T>::Call() instantiation inside lego1.

https://claude.ai/code/session_01HHMmowothg25fephi6iidq

* Guard IsMultiplayerRejected with EXTENSIONS ifdef

extensions.cpp is only compiled when ISLE_EXTENSIONS is ON, so the
wrapper function and its call site need #ifdef EXTENSIONS guards for
targets like x86 MSVC where extensions are disabled.

https://claude.ai/code/session_01HHMmowothg25fephi6iidq

* Move IsMultiplayerRejected definition to multiplayer.cpp

The function is declared in multiplayer.h and belongs with the rest of
the multiplayer extension code, not in the general extensions.cpp file.

https://claude.ai/code/session_01HHMmowothg25fephi6iidq

---------

Co-authored-by: Claude <noreply@anthropic.com>

ISLE/isleapp.cpp

@@ -37,7 +37,6 @@
 #include "viewmanager/viewmanager.h"
 
 #include <array>
-#include <extensions/extensions.h>
 #include <extensions/multiplayer.h>
 #include <miniwin/miniwindevice.h>
 #include <type_traits>
@@ -1297,10 +1296,12 @@ inline bool IsleApp::Tick()
 		return true;
 	}
 
-	if (Extension<MultiplayerExt>::Call(CheckRejected).value_or(FALSE)) {
+#ifdef EXTENSIONS
+	if (Extensions::IsMultiplayerRejected()) {
 		g_closed = TRUE;
 		return true;
 	}
+#endif
 
 	if (!TickleManager()) {
 		return true;

extensions/include/extensions/multiplayer.h

@@ -45,6 +45,8 @@ class MultiplayerExt {
 };
 
 #ifdef EXTENSIONS
+LEGO1_EXPORT bool IsMultiplayerRejected();
+
 constexpr auto HandleWorldEnable = &MultiplayerExt::HandleWorldEnable;
 constexpr auto HandleEntityNotify = &MultiplayerExt::HandleEntityNotify;
 constexpr auto CheckRejected = &MultiplayerExt::CheckRejected;

extensions/src/multiplayer.cpp

@@ -1,5 +1,6 @@
 #include "extensions/multiplayer.h"
 
+#include "extensions/extensions.h"
 #include "extensions/multiplayer/networkmanager.h"
 #include "extensions/multiplayer/networktransport.h"
 #include "extensions/multiplayer/protocol.h"
@@ -118,3 +119,8 @@ Multiplayer::NetworkManager* MultiplayerExt::GetNetworkManager()
 {
 	return s_networkManager;
 }
+
+bool Extensions::IsMultiplayerRejected()
+{
+	return Extension<MultiplayerExt>::Call(CheckRejected).value_or(FALSE);
+}