The project was Makefile-only and non-portable. Adds a top-level
CMakeLists.txt so the framework builds with a standard build system:
* add_library(JTest STATIC ...) over the 13 src/JTest/*.cpp translation
units. No find_package/FetchContent is needed: a full #include scan of
include/, src/, examples/ shows the framework depends only on the C++
standard library plus its own <JTest/...> headers.
* target_include_directories(JTest PUBLIC include) so consumers that link
JTest (the example, tests) inherit the include path transitively.
* target_compile_features(JTest PUBLIC cxx_std_17) propagates the C++17
requirement (sources use std::optional).
* Portable (no -arch) build: the Makefile's non-portable -arch flag is not
carried over (that is T-20's scope).
* enable_testing() + add_test() running tests/smoke.cpp, a genuine self-check
that exercises the public API and exits non-zero on any failed assertion, so
ctest is a real pass/fail gate. The demo example remains a build/run target
but is intentionally excluded from the CTest gate (it contains deliberate
failing/skipping cases to showcase reporting and always exits 0).
Verified end-to-end (CMake 4.4.3, AppleClang 21, out-of-source build):
configure OK, builds libJTest.a + example + test_smoke, ctest passes
(smoke: Passed, 100%), example demo runs.
