feat(libmeanfield): centrifugal + pressure

libmeanfield/interface/physics/context.cppm

@@ -1,4 +1,5 @@
 module;
+#include <memory>
 #include <mfem.hpp>
 
 export module mean_field:physics.contexts;
@@ -23,6 +24,6 @@ export namespace mean_field::physics {
         std::unique_ptr<mfem::HypreParMatrix> Schur;
 
         std::unique_ptr<mfem::MatrixCoefficient> mapped_hdiv_mass_coeff;
-
+        std::unique_ptr<mfem::Operator> source_form;
     };
-}
+} // namespace mean_field::physics