feat: add analysis model objects

tests/load/load_base_test.cpp

@@ -0,0 +1,30 @@
+#include "fesa/load/Load.hpp"
+#include "fesa/load/NodalLoad.hpp"
+
+#include <memory>
+
+namespace {
+
+int require(bool condition) {
+    return condition ? 0 : 1;
+}
+
+} // namespace
+
+int run_load_base_tests() {
+    std::unique_ptr<fesa::load::Load> owned =
+        std::make_unique<fesa::load::NodalLoad>(1, fesa::core::Dof::U3, -100.0);
+    const fesa::load::Load& load = *owned;
+    const auto& nodal = static_cast<const fesa::load::NodalLoad&>(load);
+
+    if (const int result = require(load.kind() == fesa::load::LoadKind::Nodal); result != 0) {
+        return result;
+    }
+    if (const int result = require(nodal.nodeId() == 1); result != 0) {
+        return result;
+    }
+    if (const int result = require(nodal.dof() == fesa::core::Dof::U3); result != 0) {
+        return result;
+    }
+    return require(nodal.value() == -100.0);
+}