feat: add solver core skeleton

tests/unit/model_boundary_condition_test.cpp

@@ -0,0 +1,11 @@
+#include <fesa/model/boundary_condition.hpp>
+
+int main()
+{
+    const fesa::model::BoundaryCondition bc{
+        fesa::core::NodeId{1},
+        fesa::model::DofComponent::ux,
+        0.0
+    };
+    return bc.node_id().value == 1 ? 0 : 1;
+}