Integrate Refactor solver sources and dual MSVC CMake builds

include/fesa/elements/mitc4_shell_definition.h

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+#ifndef FESA_ELEMENTS_MITC4_SHELL_DEFINITION_H_
+#define FESA_ELEMENTS_MITC4_SHELL_DEFINITION_H_
+
+#include <array>
+#include <string_view>
+#include <vector>
+
+#include "fesa/elements/element_definition.h"
+
+namespace fesa {
+
+class Domain;
+
+/// @brief Preserves the source shell type independently of formulation.
+enum class ShellSourceElementType { kS4, kS4r };
+
+/// @brief Names the internal shell formulation selected by S4 and S4R.
+inline constexpr std::string_view kMitc4InternalFormulation{"FESA-MITC4"};
+
+/// @brief Defines one four-node S4/S4R semantic element.
+class Mitc4ShellDefinition final : public ElementDefinition {
+ public:
+  /// @brief Constructs a parser-validated semantic definition.
+  Mitc4ShellDefinition(SourceEntityId source_id,
+                       ShellSourceElementType source_type,
+                       std::array<EntityIndex, 4> node_indices,
+                       EntityIndex material_index, EntityIndex section_index,
+                       SourceLocation location);
+
+  ElementDefinitionKind Kind() const noexcept override;
+  const SourceEntityId& SourceId() const noexcept override;
+  std::string_view SourceElementType() const noexcept override;
+  const std::vector<EntityIndex>& NodeIndices() const noexcept override;
+  EntityIndex MaterialIndex() const noexcept override;
+  EntityIndex PropertyIndex() const noexcept override;
+
+  SourceEntityId source_id;
+  ShellSourceElementType source_type;
+  std::array<EntityIndex, 4> node_indices;
+  EntityIndex material_index;
+  EntityIndex section_index;
+  SourceLocation location;
+
+ private:
+  friend class Domain;
+
+  /// @brief Rebinds a shell-local section index to the unified property view.
+  void SetPropertyIndex(EntityIndex property_index) noexcept;
+
+  /// @brief Synchronizes the base view after parser-candidate construction.
+  void SynchronizeNodeIndices();
+
+  EntityIndex property_index_;
+  std::vector<EntityIndex> node_indices_view_;
+};
+
+
+}  // namespace fesa
+
+#endif  // FESA_ELEMENTS_MITC4_SHELL_DEFINITION_H_