feat: add C++ support with ImGui/ImPlot framework and vendor submodules

Añade soporte C++ al registry: vendor submodules (glfw, imgui, implot, tracy),
sistema de build con CMake y toolchains cross-platform, runner C++ en fn CLI,
parser de tests Google Test, y funciones bash para build Linux/Windows.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cpp/functions/viz/bar_chart.h

@@ -0,0 +1,6 @@
+#pragma once
+
+// Renders a vertical bar chart using ImPlot.
+// Call within an ImGui frame.
+void bar_chart(const char* title, const char* const* labels, const float* values, int count, float bar_width = 0.67f);
+void bar_chart(const char* title, const char* const* labels, const double* values, int count, double bar_width = 0.67);