Batch processing

[maragall]

Add neighborhood-aware tile registration batching

• Implement Neighborhood dataclass to group tiles with their required left/top neighbors
• Add memory-constrained batching that keeps neighbor relationships within same batch
• Replace sequential file-based batching with neighborhood-aware processing
• Remove duplicate register_tiles function, consolidate to register_tiles_batched
• Preserve NaN values in neighbor assignment to prevent invalid tile relationships
• Add comprehensive grid structure and neighbor assignment debugging
• Update module exports to use unified batched registration function
• Guarantee translation computation completeness for all valid tile pairs