Update: Using C++26 with contracts enabled

cppcheck/suppressions.txt

@@ -0,0 +1,8 @@
+# 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