feat: add C++ ImGui functions for core UI and visualization

Funciones C++/ImGui para dashboards (grid, panel, docking, sidebar, tabs),
visualizaciones (candlestick, gauge, histogram, pie, sparkline, heatmap,
scatter, line, bar, surface3d, kpi, table), grafos (force layout, renderer,
viewport, spatial hash, types) y utilidades (time series buffer, tracy zones,
memory/fps overlay, plot theme).

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

cpp/functions/viz/sparkline.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include "imgui.h"
+
+// Renders a mini inline line chart for use in tables, headers and KPI cards.
+// Auto-scales Y to the min/max of values.
+// Uses PushID/PopID with id for uniqueness inside tables.
+void sparkline(const char* id, const float* values, int count,
+               float width = 100.0f, float height = 20.0f);
+
+void sparkline(const char* id, const float* values, int count, ImVec4 color,
+               float width = 100.0f, float height = 20.0f);