Replaced the memory-intensive full image read of per-tile orthophotos with a windowed read from the global Ortho VRT. This fixes memory crashes and ensures correct texture coverage for buildings that cross tile boundaries.
Improved performance and reduced disk I/O by using GDAL's MEM driver for intermediate warp operations. The warped dataset is now passed directly to the translate step without being written to a temporary file.
Optimized memory usage by reading only the required pixel window from the heightmap VRT instead of loading the entire dataset into memory. This prevents crashes on large datasets while maintaining scientific accuracy for ground-snapping.
Refactored the subprocess wrapper to only split the command part (first element) if it contains spaces, while preserving spaces in subsequent arguments (like file paths). Added unit tests for various scenarios including command overrides and error handling.
