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/graph_force_layout.h

@@ -0,0 +1,27 @@
+#pragma once
+
+struct GraphData; // forward declare
+
+struct ForceLayoutConfig {
+    float repulsion    = 500.0f;  // repulsion strength between all nodes
+    float attraction   = 0.01f;   // spring constant for edges
+    float damping      = 0.85f;   // velocity decay per step
+    float min_distance = 1.0f;    // minimum distance (avoid division by zero)
+    float theta        = 0.5f;    // Barnes-Hut threshold (0 = exact, 1 = fast)
+    float gravity      = 0.1f;    // pull toward center (prevents drift)
+    float max_velocity = 50.0f;   // cap velocity per axis
+    int   iterations   = 1;       // steps per call
+};
+
+// Perform one (or more) steps of force-directed layout.
+// Modifies node positions (x, y) and velocities (vx, vy) in-place.
+// Returns the total kinetic energy (sum of |v|^2). When energy < threshold,
+// layout has converged.
+float graph_force_layout_step(GraphData& graph, const ForceLayoutConfig& config = {});
+
+// Reset: randomize positions within [-spread, spread], zero velocities.
+void graph_force_layout_reset(GraphData& graph, float spread = 200.0f);
+
+// Preset layouts (non-iterative, instant positioning)
+void graph_layout_circular(GraphData& graph, float radius = 100.0f);
+void graph_layout_grid(GraphData& graph, float spacing = 20.0f);