crop.drag {handle, from, to, start?} runs drag_crop through the command
layer so the UI, CLI, control channel and MCP agree; a locked crop keeps the
shape of its frame. crop.aspect now rejects non-finite, non-positive and
beyond-20:1 ratios and non-numeric arrays instead of storing a degenerate
lock that produced an empty crop.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>