refactor(polytropeOperator.h): changed to nested namespace

src/polytrope/utils/public/polytropeOperator.h

@@ -26,8 +26,7 @@
 
 #include "probe.h"
 
-namespace serif {
-namespace polytrope {
+namespace serif::polytrope {
 
 /**
  * @brief Represents the Schur complement operator used in the solution process.
@@ -299,7 +298,7 @@ private:
     std::unique_ptr<mfem::MixedBilinearForm> m_M; ///< Bilinear form M, coupling θ and φ.
     std::unique_ptr<mfem::MixedBilinearForm> m_Q; ///< Bilinear form Q, coupling φ and θ.
     std::unique_ptr<mfem::BilinearForm> m_D;      ///< Bilinear form D, acting on φ.
-    std::unique_ptr<mfem::BilinearForm> m_S;
+    std::unique_ptr<mfem::BilinearForm> m_S;      ///< Bilinear form S, used for least squares stabilization.
     std::unique_ptr<mfem::NonlinearForm> m_f;     ///< Nonlinear form f, acting on θ.
 
     // --- Full Matrix Representations (owned, derived from forms) ---
@@ -395,5 +394,4 @@ private:
     void update_preconditioner(const mfem::Operator &grad) const;
 };
 
-} // namespace polytrope
-} // namespace serif
+} // namespace serif::polytrope