Rework tiling

[ma595]

Tiling function needs to be broken down into smaller functions. Introduce pathlib.

[PatBall1]

Closing as largely addressed. The tiling code has been refactored with tqdm progress bars and pathlib (PR #206, merged Jan 2026), and new features have been added (full_coverage, multithreaded tiling, adaptive placement, etc.). The function is now modular with internal helpers like _calculate_tile_placements, process_tile_train, etc.