feat: implement consistent-mass HHT shell dynamics

include/fesa/analysis/newton_iteration_log.h

@@ -1,6 +1,7 @@
 #ifndef FESA_ANALYSIS_NEWTON_ITERATION_LOG_H_
 #define FESA_ANALYSIS_NEWTON_ITERATION_LOG_H_
 
+#include <array>
 #include <cstdint>
 #include <filesystem>
 #include <fstream>
@@ -49,6 +50,27 @@ struct NewtonIterationLogRecord {
   bool combined_passed;
 };
 
+/// @brief Carries two-channel HHT endpoint convergence evidence.
+/// @note Array entries are translation and rotation channels, respectively.
+/// Corrections are dimensionless N2 metrics; rate corrections already include
+/// h or h squared. Residual numerator and scale retain force/moment units.
+struct DynamicNewtonIterationLogRecord {
+  std::uint32_t increment_index = 0U;
+  std::uint32_t iteration_index = 0U;
+  double time = 0.0;
+  std::string stage;
+  std::string outcome;
+  std::string failure_code;
+  std::array<double, 2U> residual_numerator{};
+  std::array<double, 2U> residual_scale{};
+  std::array<double, 2U> coordinate_correction{};
+  std::array<double, 2U> velocity_correction{};
+  std::array<double, 2U> acceleration_correction{};
+  std::array<double, 2U> algorithmic_correction{};
+  bool residual_pass = false;
+  bool correction_pass = false;
+};
+
 /// @brief Writes deterministic, line-oriented Newton iteration diagnostics.
 /// @note A write, flush, or close failure permanently prevents a successful
 /// log lifecycle for this writer instance.
@@ -66,6 +88,11 @@ class NewtonIterationLogWriter {
   /// failure with code `log-output-failure`.
   Status Write(const NewtonIterationLogRecord& record);
 
+  /// @brief Writes one complete HHT record using schema `hht-log-v1`.
+  /// @return Success after the complete line is written; invalid numeric
+  /// evidence or stream failure permanently fails this writer instance.
+  Status Write(const DynamicNewtonIterationLogRecord& record);
+
   /// @brief Flushes every complete record written so far to the log.
   /// @return Success after the stream flush, otherwise an output failure with
   /// code `log-output-failure`.