[newmana]

Backwards compatible speedup/memory reduction improvement.

Changes:

• run stores the neighbours as a graph, adata.obsp["spot_neighbours"] (int8 CSR, row i’s indices spot i’s neighbours)
• Per spot (obsm["spot_neighbours"] and obsm["spot_neigh_bcs"]) are removed. These consume ~25% of the runtime and large amount of memory.
• get_neighbourhoods reads obsp first and falls back to obsm strings written previously.
• score_spots finds each chunk’s rows with a boolean mask and position lookup instead of using np.unique.
• The neighbour graph is built once and passed through get_lrs_scores and perform_spot_testing; LRScorer accepts it directly (List | csr_matrix).