feat: add thermal semantic domain model

include/fesa/model/domain.h

@@ -183,6 +183,30 @@ class Domain {
   const DomainCollectionView<LinearElasticMaterial>& LinearElasticMaterials()
       const noexcept;
 
+  /// @brief Returns thermal materials in stable thermal declaration order.
+  const DomainCollectionView<IsotropicThermalMaterial>& ThermalMaterials()
+      const noexcept;
+
+  /// @brief Returns DS4 definitions in stable thermal declaration order.
+  const DomainCollectionView<Ds4ThermalDefinition>& ThermalElements()
+      const noexcept;
+
+  /// @brief Returns centered thermal shell assignments in declaration order.
+  const std::vector<ThermalShellSectionDefinition>& ThermalSections()
+      const noexcept;
+
+  /// @brief Returns resolved initial temperatures in source order.
+  const std::vector<ThermalInitialConditionDefinition>&
+  ThermalInitialConditions() const noexcept;
+
+  /// @brief Returns model-level thermal boundary definitions in source order.
+  const std::vector<ThermalBoundaryConditionDefinition>&
+  ThermalModelBoundaries() const noexcept;
+
+  /// @brief Returns the sole thermal step, or null when the model is
+  /// structural.
+  const ThermalStepDefinition* ThermalStep() const noexcept;
+
   /// @brief Returns all properties in stable Domain index order.
   const DomainCollectionView<ElementProperty>& Properties() const noexcept;
 
@@ -243,6 +267,8 @@ class Domain {
   DomainCollectionView<ShellSection> shell_sections_view_;
   DomainCollectionView<Material> materials_view_;
   DomainCollectionView<LinearElasticMaterial> linear_materials_view_;
+  DomainCollectionView<IsotropicThermalMaterial> thermal_materials_view_;
+  DomainCollectionView<Ds4ThermalDefinition> thermal_elements_view_;
   DomainCollectionView<StepDefinition> steps_view_;
 };