Escape the Haunted Castle (Part 1)

You are given a grid of size rows × cols representing a haunted castle. Some cells are walls (impassable), and there are designated endpoints (start and exit). Each step you can move to an orthogonally adjacent cell (up/down/left/right) that is not a wall.

Implement classes/functions to represent the grid, walls, and endpoints, plus a function that finds a path from the start to the exit through valid cells and reports the sequence of cells visited.

Example: rows=2, cols=2, walls=[[0,1]], start=[0,0], end=[1,1] → [(0,0),(1,0),(1,1)] (length 3 = 2 steps).