port(2P step 3a/3b): stdlib on sys.path + the pack module

step 3a — 标准库:
  tools/py_embed/make_stdlib_zip.py packs the vendored Lib/ into
  <build>/python27.zip (397 modules, 6876547 bytes, ZIP_STORED — the zlib
  module is trimmed out of our CPython, so zipimport cannot inflate).
  The mtpython_stdlib target builds it; py_embed_test and the launcher test
  both run against it.
  platform/ScriptLib/PythonHost sets the embedding flags before
  Py_Initialize and, after it, puts the zip on sys.path and re-registers
  encodings.search_function with codecs — 2.7 builds the codec registry
  once, at startup, so replacing sys.path afterwards needs it back.

step 3b — pack 模块:
  UserInterface/PythonPackModule.cpp copied verbatim; packExist/packGet/
  initpack read root/ and uiscript/ through CEterPackManager, i.e. through
  asset_io. The CHINA_CRYPT_KEY block in that unit is CAccountConnector's
  and is kept #if 0 until the login slice (2V1). UserInterface/StdAfx.h is
  a documented partial mirror — the original is the whole client's PCH.

The launcher test now runs initpack() as RunMainScript does (its first
line), reads system.py / uiscript / locale text back out of the packs, and
confirms cp1252 decoding works off the zip. system.py still stops at
"No module named app" — the C++ modules are the 2V0 slice.

gates: port_map.py check 0 errors · key leak check 8/8 none · macOS ctest
27/27 · android + ios port_platform compile clean.

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

extension/CMakeLists.txt

@@ -159,10 +159,9 @@ if(BUILD_TESTING AND MT_HOST_BUILD)
     if(TARGET mtpython)
         add_executable(py_embed_test tests/py_embed_test.cpp)
         target_link_libraries(py_embed_test PRIVATE mtpython)
-        # The stdlib the host puts on sys.path: here the vendored Lib/ directly (batch 2P step 3 ships
-        # it as python27.zip).
-        add_test(NAME python.embed COMMAND $<TARGET_FILE:py_embed_test>
-                 "${CMAKE_CURRENT_SOURCE_DIR}/third_party/cpython-2.7.18/Lib")
+        add_dependencies(py_embed_test mtpython_stdlib)
+        # The stdlib exactly as the host ships it: python27.zip, read through zipimport (批次 2P step 3).
+        add_test(NAME python.embed COMMAND $<TARGET_FILE:py_embed_test> "${MT_PYTHON_STDLIB_ZIP}")
     endif()
 endif()