Update: Using C++26 with contracts enabled

cppcheck/suppressions.txt

@@ -1,8 +0,0 @@
-# Suppress Cppcheck noise for this GCC 16 / C++26 project.
-#
-# The CLion Cppcheck plugin analyzes headers in isolation and often reports
-# false positives (missing system includes, GCC libstdc++ syntax errors).
-# Prefer: cmake --build build --target cppcheck_modules
-
-missingIncludeSystem
-syntaxError