🧭 Pathfinding on Weighted Terrain — 2D Search Map: BFS, Dijkstra, A* and Greedy Frontier Heatmap

2D companion of the weighted-terrain pathfinding lab: a top-down map with an expansion-order heatmap, frontier, paintable terrain, side-by-side comparison of BFS, Dijkstra, A* and greedy search, and a weight sweep showing the speed versus optimality trade-off.