[codex] Add synchronous named pipe client

[LimiNode]

What Changed

• Added NamedPipeClient with synchronous connect/open, write, blocking read, try_read, timeout read, available, flush, and basic callbacks.
• Added ClientConfig for pipe name, buffer size, and timeout.
• Added a SimpleNamedPipeClient static target and wired it into examples/tests when static mode is enabled.
• Added a Windows client_server_test that starts NamedPipeServer, connects the C++ client, sends ping, and reads Echo: ping.
• Extended ODR compile coverage to include NamedPipeClient.hpp.
• Fixed static-library mode for .ipp implementations by emitting out-of-line definitions when SIMPLE_NAMED_PIPE_STATIC_LIB is set, while keeping inline definitions for header-only mode.
• Documented the minimal C++ client in README.md.

Why

SimpleNamedPipe had a solid C++ server and an MQL5 client, but no C++ client for tests or lightweight local integrations. optionx_cpp needs a C++ client-side pipe API before adding a legacy bridge based on this library.

The new integration test also exposed that static-library consumers no longer received symbols after the server implementation was made inline. The SIMPLE_NAMED_PIPE_INLINE macro preserves both modes: header-only remains inline and static-library builds produce real symbols.

Validation

• cmake -S . -B build-codex-mingw -G "MinGW Makefiles" -DSIMPLE_NAMED_PIPE_BUILD_TESTS=ON
• cmake --build build-codex-mingw --target client_server_test --parallel 4
• ./build-codex-mingw/client_server_test.exe
• cmake --build build-codex-mingw --parallel 4
• cmake -S . -B build-codex-header -G "MinGW Makefiles" -DSIMPLE_NAMED_PIPE_BUILD_TESTS=ON -DSIMPLE_NAMED_PIPE_BUILD_STATIC=OFF
• cmake --build build-codex-header --target client_server_test --parallel 4
• ./build-codex-header/client_server_test.exe
• Manual ODR command equivalent to tests/odr/run_odr_test.sh using g++, tests/stubs, and both ODR translation units.
• git diff --check

Note: local PowerShell environment does not have bash, so the shell wrapper itself was not run locally. The same compile/link commands were executed manually; GitHub Ubuntu workflow should still run the script.