refactor: modules support redesigned

example/include/geographic.h

@@ -23,7 +23,7 @@
 #pragma once
 
 #include "ranged_representation.h"
-#include <mp-units/bits/fmt_hacks.h>
+#include <mp-units/compat_fmt_macros.h>
 #include <compare>
 #include <limits>
 #include <numbers>
@@ -33,11 +33,10 @@ import mp_units;
 #else
 #include <mp-units/compare.h>
 #include <mp-units/format.h>
-#include <mp-units/math.h>
 #include <mp-units/quantity.h>
 #include <mp-units/quantity_point.h>
 #include <mp-units/systems/isq/space_and_time.h>
-#include <mp-units/systems/si/units.h>
+#include <mp-units/systems/si/si.h>
 #endif
 
 namespace geographic {