action: /shape/{curve.key} fills placeholders from the submitted
responses and must land on a dynamic page (validated). The gesture
widget now treats relay 'place' (kept) and 'echo' (live presence)
frames as pickable options: picking one re-derives the input's key -
that place's decode becomes the ghost under the stroke and the answer
records {key: picked, own_key, selected_from, selected_distance}, the
labelled pair that later ranks places and calibrates the key. Dedupe
by key; an empty state when nothing is kept at the shape.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
