port 2P step 1: vendor CPython 2.7.18 as the mtpython static library

The embedded 40250 script layer needs its own interpreter on five platforms.
2.7 is end-of-life, so nothing can be fetched from the target SDKs and the
source is vendored (official 2.7.18 tarball, trimmed to 25MB; Lib/ stays for
step 3's python27.zip).

cpython-2.7.18/CMakeLists.txt builds one `mtpython` static library from exactly
the 133 objects the reference libpython2.7.a contains, off by default behind
-DMTGODOT_EMBED_PYTHON=ON. The source list and the built-in module table
(config/config.c, 39 entries) are shared; pyconfig.h is a probe result and is
not, so each platform keeps its own under config/<platform>/, regenerated by
tools/py_embed/gen_pyconfig.sh and checked against the shared table.

Three vendor patches, documented in docs/THIRD-PARTY.md: configure/configure.ac
learn arm64 on macOS, and posixmodule.c undefines the process-control calls it
hard-defines past pyconfig.h when building for iOS.

macOS (ctest python.embed: every builtin imports, codecs and pickle work off the
vendored Lib/), Android arm64 and iOS arm64 build. Linux needs a Linux host and
Windows needs a MinGW-vs-MSVC decision; both are noted for step 4.

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

extension/third_party/cpython-2.7.18/Lib/wsgiref/__init__.py

@@ -0,0 +1,23 @@
+"""wsgiref -- a WSGI (PEP 333) Reference Library
+
+Current Contents:
+
+* util -- Miscellaneous useful functions and wrappers
+
+* headers -- Manage response headers
+
+* handlers -- base classes for server/gateway implementations
+
+* simple_server -- a simple BaseHTTPServer that supports WSGI
+
+* validate -- validation wrapper that sits between an app and a server
+  to detect errors in either
+
+To-Do:
+
+* cgi_gateway -- Run WSGI apps under CGI (pending a deployment standard)
+
+* cgi_wrapper -- Run CGI apps under WSGI
+
+* router -- a simple middleware component that handles URL traversal
+"""