Add client-only channel switch (AVA2 ENABLE_CHANNEL_CHANGE)

mt_channel lists the serverInfo channels of the current server and switches by
running the original paths: /logout, then the login window connects to the
chosen channel with the account kept by MainStream, and the original
stream.isAutoSelect starts the same character. No server change.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/platform/ScriptLib/PythonBoot.cpp

@@ -1002,6 +1002,7 @@ namespace PythonBoot
 #include "SwitchbotScript.inc"
 #include "PickupScript.inc"
 #include "DisplayScript.inc"
+#include "ChannelScript.inc"
 
 static void install_script_module(const char* c_szModule, const char* c_szScript)
 {
@@ -1078,6 +1079,7 @@ bool RunMainScript(const char* lpCmdLine, std::string* error)
 		install_script_module("mt_switchbot", c_szSwitchbotScript);
 		install_script_module("mt_pickup", c_szPickupScript);
 		install_script_module("mt_display", c_szDisplayScript);
+		install_script_module("mt_channel", c_szChannelScript);
 		if (g_touch_input)
 			install_script_module("mt_mobile_hud", c_szMobileHUDScript);
 	}