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/curses/wrapper.py

@@ -0,0 +1,50 @@
+"""curses.wrapper
+
+Contains one function, wrapper(), which runs another function which
+should be the rest of your curses-based application.  If the
+application raises an exception, wrapper() will restore the terminal
+to a sane state so you can read the resulting traceback.
+
+"""
+
+import curses
+
+def wrapper(func, *args, **kwds):
+    """Wrapper function that initializes curses and calls another function,
+    restoring normal keyboard/screen behavior on error.
+    The callable object 'func' is then passed the main window 'stdscr'
+    as its first argument, followed by any other arguments passed to
+    wrapper().
+    """
+
+    try:
+        # Initialize curses
+        stdscr = curses.initscr()
+
+        # Turn off echoing of keys, and enter cbreak mode,
+        # where no buffering is performed on keyboard input
+        curses.noecho()
+        curses.cbreak()
+
+        # In keypad mode, escape sequences for special keys
+        # (like the cursor keys) will be interpreted and
+        # a special value like curses.KEY_LEFT will be returned
+        stdscr.keypad(1)
+
+        # Start color, too.  Harmless if the terminal doesn't have
+        # color; user can test with has_color() later on.  The try/catch
+        # works around a minor bit of over-conscientiousness in the curses
+        # module -- the error return from C start_color() is ignorable.
+        try:
+            curses.start_color()
+        except:
+            pass
+
+        return func(stdscr, *args, **kwds)
+    finally:
+        # Set everything back to normal
+        if 'stdscr' in locals():
+            stdscr.keypad(0)
+            curses.echo()
+            curses.nocbreak()
+            curses.endwin()