feat: implement consistent-mass HHT shell dynamics

include/fesa/io/hdf5/dynamic_hdf5_results_writer.h

@@ -0,0 +1,20 @@
+#ifndef FESA_IO_HDF5_DYNAMIC_HDF5_RESULTS_WRITER_H_
+#define FESA_IO_HDF5_DYNAMIC_HDF5_RESULTS_WRITER_H_
+
+#include "fesa/results/dynamic_results_writer.h"
+
+namespace fesa {
+
+/// @brief Writes schema-v1 HHT dynamic HDF5 results with atomic finalization.
+class DynamicHdf5ResultsWriter final : public DynamicResultsWriter {
+ public:
+  /// @brief Writes a validated dynamic result file and preserves a prior final
+  /// file on failure.
+  Status Write(const std::filesystem::path& output_path, const Domain& domain,
+               const DynamicAnalysisState& state,
+               const std::vector<Diagnostic>& diagnostics) override;
+};
+
+}  // namespace fesa
+
+#endif  // FESA_IO_HDF5_DYNAMIC_HDF5_RESULTS_WRITER_H_