Fix #143: SystemLink Cmake module is unnecessary complexity

[leftibot]

Automated fix by @leftibot.

What changed

Fix #143: Remove SystemLink.cmake, use CPM SYSTEM option instead
The SystemLink.cmake module performed complex operations at link-site to
mark imported dependency headers as system includes. This is unnecessary
since CPM supports a SYSTEM option that passes SYSTEM to add_subdirectory,
causing CMake (>= 3.25) to treat all targets from that subdirectory as
system includes natively. All CPMAddPackage calls now use SYSTEM YES,
the target_link_system_libraries call is replaced with plain
target_link_libraries, and SystemLink.cmake is removed entirely.
Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Files

 Dependencies.cmake                  | 52 ++++++++++++++++++++---
 ProjectOptions.cmake                |  1 -
 cmake/SystemLink.cmake              | 83 -------------------------------------
 src/ftxui_sample/CMakeLists.txt     |  6 +--
 test/CMakeLists.txt                 | 14 +++++++
 test/check_system_includes.cmake.in | 13 ++++++
 6 files changed, 75 insertions(+), 94 deletions(-)

Closes #143

Triggered by @lefticus.

[lefticus]

@leftibot remove CMake test scripts, that will be confusing to end user, and don't include lefticus tools as a system include

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 20.50%. Comparing base (12e3e37) to head (c5426d7).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #145   +/-   ##
=======================================
  Coverage   20.50%   20.50%           
=======================================
  Files           5        5           
  Lines         239      239           
  Branches      108      110    +2     
=======================================
  Hits           49       49           
+ Misses        186      181    -5     
- Partials        4        9    +5     

Flag	Coverage Δ
Linux	18.36% <ø> (ø)
Windows	21.02% <ø> (ø)
macOS	18.87% <ø> (ø)

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[leftibot]

Addressed review feedback from @lefticus. New commits:

c5426d7 Address review: remove CMake test scripts, don't SYSTEM-include lefticus tools

[leftibot]

Hi @lefticus — I tried to address the review feedback but couldn't produce a working change. May need human attention.

[leftibot]

Hi @lefticus — I tried to address the review feedback but couldn't produce a working change. May need human attention.