Improve physical geometry, fluid solvers, audio, and profiling

include/FluidSim/TwoStrokeConfig.hpp

@@ -1,7 +1,9 @@
 #pragma once
+#include "FluidSim/MeshResolution.hpp"
 #include "FluidSim/PipeProfile.hpp"
 #include "FluidSim/Ecu.hpp"
 #include "FluidSim/Vehicle.hpp"
+#include "FluidSim/PhysicalGeometry.hpp"
 #include <array>
 
 namespace fluidsim::port {
@@ -10,6 +12,8 @@ enum class TwoStrokeExhaust { Racing, Straight };
 // YZ125-sized baseline. Port/chamber/combustion dimensions are explicit design
 // estimates, not a measured Yamaha cylinder or factory exhaust/ignition map.
 struct TwoStrokeConfig {
+    PhysicalGeometry geometry;
+    float cells_per_meter{}; // Zero retains legacy programmatic meshes. TOML scenarios specify a density.
     EcuConfig ecu=[] {
         EcuConfig e;
         e.idle_control=EcuConfig::IdleControl::FixedOpening;
@@ -42,6 +46,7 @@ struct TwoStrokeConfig {
     float jet_scale{1.f}; // multiplier on effective jet diameters
     float crankcase_clearance{150e-6f};
     float carburetor_diameter{.0381f};
+    float reed_pipe_diameter{.040f},transfer_pipe_diameter{.032f};
     float idle_spark_gain{.05f}; // spark degrees per RPM error at the fixed carb stop
     float idle_minimum_advance{-10.f};
     float idle_slide_opening{.045f}; // fixed mechanical stop, normalized 0..1 (4.5%)