2V1-b/c: PythonNetworkStream phases, AccountConnector and the net module

Port PythonNetworkStream with its HandShake/Login/Select/Loading/Offline
phases, AccountConnector and PythonNetworkStreamModule verbatim; the net
stub goes. PythonBoot creates the network stream, account connector,
player, flying manager and effect manager like CPythonApplication, and
app.Create/Process drive CNetworkDevice and both connectors.

Packet.h long fields become 32-bit LONG; port.packet checks 38
login/select/loading packet sizes against wire_classic.h. Unported units
in the link closure live under platform/pending/ as stand-ins. The macOS
gate now builds all and finds iconv.

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

extension/src/port/common/shim/sdk/Python-2.7/grammar.h

@@ -7,3 +7,8 @@
 // alone under the port header gate.
 #include <Python.h>
 #include <grammar.h>
+// CPython's bitset.h (pulled in by grammar.h) does `#define BYTE char`; the copy under 40250's
+// extern/include/Python-2.7 has that line removed, so BYTE stays the Win32 unsigned char in every
+// file that includes ScriptLib/StdAfx.h. bitset.h's own macros only use sizeof(BYTE), which is 1
+// either way.
+#undef BYTE

extension/src/port/common/shim/win32/windows.h

@@ -28,3 +28,6 @@
 #define VK_HOME 0x24
 #define VK_END 0x23
 #define VK_DELETE 0x2E
+
+// winuser.h functions the platform layer implements (platform/ScriptLib/PythonBoot.cpp).
+void PostQuitMessage(int nExitCode);