Improve physical geometry, fluid solvers, audio, and profiling

include/FluidSim/AudioProcessing.hpp

@@ -3,7 +3,7 @@
 namespace fluidsim::port {
 
 struct AudioFrame { float left{}, right{}; };
-struct Vec3 { float x{}, y{}, z{}; };
+struct Vec3 { float x{}, y{}, z{}; bool operator==(const Vec3&) const = default; };
 struct AudioListener { Vec3 position{}, right{1,0,0}; };
 
 // Simple flow-derivative source used by the Helmholtz and pulse scenarios.