Connect MITC4 drilling evidence across analysis procedures

include/fesa/analysis/eigen_analysis_state.h

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "fesa/math/matrix.h"
+#include "fesa/elements/mitc4_drilling_mode.h"
 #include "fesa/solvers/eigen/eigen_solver.h"
 
 namespace fesa {
@@ -53,6 +54,7 @@ struct EigenAnalysisState {
   explicit EigenAnalysisState(FeastEigenResult backend_result)
       : backend{std::move(backend_result)} {}
 
+  std::optional<Mitc4DrillingMode> drilling_mode;
   std::size_t full_dof_count{0U};
   std::size_t free_dof_count{0U};
   std::size_t mass_null_dimension{0U};