feat: add solver core skeleton

tests/unit/model_property_test.cpp

@@ -0,0 +1,11 @@
+#include <fesa/model/property.hpp>
+
+int main()
+{
+    const fesa::model::Property property{
+        fesa::core::PropertyId{2},
+        "section",
+        fesa::core::MaterialId{3}
+    };
+    return property.material_id().value == 3 ? 0 : 1;
+}