feat: add thermal semantic domain model

include/fesa/materials/isotropic_thermal_material.h

@@ -0,0 +1,48 @@
+#ifndef FESA_MATERIALS_ISOTROPIC_THERMAL_MATERIAL_H_
+#define FESA_MATERIALS_ISOTROPIC_THERMAL_MATERIAL_H_
+
+#include <string>
+
+#include "fesa/core/status.h"
+#include "fesa/materials/material.h"
+
+namespace fesa {
+
+/// @brief Stores homogeneous isotropic heat-conduction material properties.
+class IsotropicThermalMaterial final : public Material {
+ public:
+  /// @brief Creates a material with finite positive conductivity, density, and
+  /// specific heat.
+  static Result<IsotropicThermalMaterial> Create(
+      SourceEntityId source_id, std::string name, double conductivity,
+      double density, double specific_heat, SourceLocation location);
+
+  MaterialKind Kind() const noexcept override;
+  const SourceEntityId& SourceId() const noexcept override;
+  const SourceLocation& Location() const noexcept override;
+
+  /// @brief Returns the source material name.
+  const std::string& Name() const noexcept;
+  /// @brief Returns conductivity in the active consistent unit system.
+  double Conductivity() const noexcept;
+  /// @brief Returns mass density in the active consistent unit system.
+  double Density() const noexcept;
+  /// @brief Returns specific heat in the active consistent unit system.
+  double SpecificHeat() const noexcept;
+
+ private:
+  IsotropicThermalMaterial(SourceEntityId source_id, std::string name,
+                           double conductivity, double density,
+                           double specific_heat, SourceLocation location);
+
+  SourceEntityId source_id_;
+  std::string name_;
+  double conductivity_;
+  double density_;
+  double specific_heat_;
+  SourceLocation location_;
+};
+
+}  // namespace fesa
+
+#endif  // FESA_MATERIALS_ISOTROPIC_THERMAL_MATERIAL_H_

include/fesa/materials/material.h

@@ -6,7 +6,7 @@
 namespace fesa {
 
 /// @brief Identifies the supported concrete material semantics.
-enum class MaterialKind { kIsotropicLinearElastic };
+enum class MaterialKind { kIsotropicLinearElastic, kIsotropicThermal };
 
 /// @brief Provides stable identity for a Domain-owned material definition.
 class Material {