feat(mean_field): added dimensions, discritization, and start of eos

The full rewrite of mean_field into something maintainable is progressing. dimensions is mostly done, discritization (domain, blocks, and fields) is done, and eos is progressing quickly

build-check/meson.build

@@ -8,6 +8,13 @@ if not cpp.has_header('memory') or not cpp.compiles('''
   error('MFEM 4.10 requires a C++17-or-newer compiler.')
 endif
 
+if not cpp.links('''
+  #include <print>
+  int main() { std::println("SERiF"); }
+''', args: platform_cpp_args + platform_link_args, name: 'C++23 std::println support')
+  error('SERiF requires C++23 std::println support. On macOS, use -Dmacos_deployment_target=15.0 or newer with a recent Xcode toolchain.')
+endif
+
 cmake_program = find_program('cmake', required: true)
 # With meson-python, the generated native file pins this to the interpreter
 # building the wheel. For command-line builds, PATH controls the selection.