Connect MITC4 drilling evidence across analysis procedures

include/fesa/analysis/nonlinear_analysis_state.h

@@ -3,6 +3,7 @@
 
 #include <array>
 #include <cstdint>
+#include <optional>
 #include <vector>
 
 #include "fesa/core/source_identity.h"
@@ -46,6 +47,7 @@ struct NonlinearTrialState {
   std::vector<ShellResultRow> shell_results;
   double physical_strain_energy;
   std::array<double, 6> global_equilibrium;
+  std::optional<Mitc4DrillingEvidence> mitc4_drilling;
 };
 
 /// @brief Stores one authoritative nonlinear increment frame.
@@ -69,6 +71,7 @@ struct AcceptedFrameState {
   std::vector<ShellResultRow> shell_results;
   double physical_strain_energy;
   std::array<double, 6> global_equilibrium;
+  std::optional<Mitc4DrillingEvidence> mitc4_drilling;
 };
 
 /// @brief Owns committed nonlinear state and validated accepted frames.