feat: add domain model foundation

tests/core/material_definition_test.cpp

@@ -0,0 +1,25 @@
+#include "fesa/core/MaterialDefinition.hpp"
+
+namespace {
+
+int require(bool condition) {
+    return condition ? 0 : 1;
+}
+
+} // namespace
+
+int run_material_definition_tests() {
+    const fesa::core::LinearElasticMaterialDefinition material{700, 210.0, 0.3};
+
+    if (const int result = require(material.id() == 700); result != 0) {
+        return result;
+    }
+    if (const int result = require(material.youngModulus() == 210.0); result != 0) {
+        return result;
+    }
+    if (const int result = require(material.poissonRatio() == 0.3); result != 0) {
+        return result;
+    }
+
+    return 0;
+}