[kaffeindecaf]

Summary

• Add a bounded nearest-neighbor pixel grid to collapse output.
• Carry up to half of previous-frame block values only in moving areas for a restrained datamosh-like smear without codec bitstream corruption.
• Expose block_size and mosh controls; update docs and benchmark data.

Verification

• Full test suite passes with optional processors installed.
• Collapse, seam, menu, and layout regressions pass; ruff passes.
• Rendered the supplied clip at 2560x1440 with original frame count and AAC audio; inspected start/middle/end frames.