feat(mean_field): added initial implementation

note this implementation lacks many tests

tests/geometry/volume.cpp

@@ -0,0 +1,25 @@
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/matchers/catch_matchers_floating_point.hpp>
+#include <catch2/benchmark/catch_benchmark.hpp>
+#include <cmath>
+#include <vector>
+#include <string>
+#include <algorithm>
+#include <mfem.hpp>
+#include <mpi.h>
+
+import mean_field;
+import test_helpers;
+
+using namespace mean_field;
+
+
+TEST_CASE("STROID Volume vs sphere", tags::geometry & tags::volume) {
+    auto args = test_utils::setup_args();
+    fem::FEM f = fem::setup_fem(args.mesh_file, args, 0);
+    const double analytic_vol = (4.0 / 3.0) * M_PI * std::pow(utils::RADIUS, 3);
+    const double stroid_vol = analysis::get_mesh_volume(f);
+
+    double s = analytic_vol / stroid_vol;
+    CHECK_THAT(stroid_vol, Catch::Matchers::WithinRel(analytic_vol, 1e-6));
+}