79e2f8b2b1
- Changed chunk edit operation format from flat `op` field to nested keyed union structure with operation name as object key. - Added parseKeyedChunkOp() function to normalize both keyed and legacy flat operation formats for backward compatibility. - Enhanced chunk selector sanitization with filename prefix stripping and case-insensitive CRC checksum matching. - Updated chunk edit prompt documentation and test suite to reflect new nested operation JSON structure.