Bind the two develop gestures that were described and not bound

FR-DEV-16's book said resetting a control and hiding a mask layer were
reachable by pointer and by finger, and stopped there. The reason was
honest: the generated rows have no focus, so "reset the focused control"
named a thing the panel could not point at. But a photographer at the
keyboard means something narrower than focus. They mean the slider they
just dragged too far, and that is a thing the panel can remember.

So the Adjustments global keeps the last control moved — two indices,
written where the panel forwards the change and cleared when the next
photograph opens, so a reset cannot reach back into the previous edit
through an index that happens to be shared. R puts it back, through the
same callback the track's double-click takes, and is silent until
something has moved.

The mask layer needs no such notion, because the panel already has a
selection: the rows the edge controls point at. H hides or shows those,
through the path the ring at the head of the row takes, so it is an edit
and a history step exactly as the ring is. A mixed selection goes to
shown, since the layer nobody can see is the one being asked about.

Both tags now carry the key, and the book says so.

ui/dr-ui/src/lib.rs

@@ -414,6 +414,12 @@ fn reset_view_state(window: &AppWindow) {
     // the first click on the *next* photograph sample it, which is a click
     // nobody meant to spend.
     window.global::<Adjustments>().set_sampling_op(-1);
+    // TRACES: FR-DEV-16
+    // And the control last moved, which R resets: the indices are into this
+    // photograph's rows, and a reset that reached back into the previous edit
+    // would land on whichever control happens to share them.
+    window.global::<Adjustments>().set_touched_op(-1);
+    window.global::<Adjustments>().set_touched_param(-1);
     // TRACES: FR-DSP-7
     // Emptied rather than left standing: the previous photograph's histogram
     // beside the next one's filename is a confident, precise lie, and the gap