Templated actions; places are pickable in the gesture input

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>

style/main.css

@@ -597,6 +597,34 @@ textarea:focus {
   opacity: var(--echo-strength, 1);
 }
 
+/* places are pickable: the pick re-derives the input's key */
+.gesture-echo {
+  cursor: pointer;
+  transition: opacity 0.5s ease, border-color 120ms, transform 120ms;
+}
+
+.gesture-echo:hover,
+.gesture-echo:focus-visible {
+  border-color: var(--accent);
+  outline: none;
+}
+
+.gesture-echo.selected {
+  border-color: var(--accent);
+  box-shadow: 0 0 0 0.12rem var(--accent);
+  transform: translateY(-0.1rem);
+}
+
+.gesture-empty {
+  margin: 0.5rem 0 0;
+  font-size: 0.85rem;
+  color: var(--ink-dim);
+}
+
+.gesture-empty:empty {
+  display: none;
+}
+
 .gesture-status {
   position: absolute;
   top: 0.55rem;