Stage 17 (#3,#5,#10): hover-hold drag zoom, always-editable profile, drag-back + double-tap recall

- Board drag now auto-zooms toward a cell after holding the tile over it ~1s (#3).
- Profile is inline-editable: drop the Edit/Cancel toggle, form is always shown
  for durable accounts; hint balance stays read-only; re-populate after link/merge (#5).
- A pending tile recalls by double-tap (same cell) or by dragging it back onto the
  rack (unzoomed board); a single tap no longer recalls (#10).
- e2e: lock double-tap recall + single-tap no-op; drop the removed Edit-profile click.

ui/src/game/Rack.svelte

@@ -21,7 +21,7 @@
   const visible = $derived(slots.filter((s) => !s.used));
 </script>
 
-<div class="rack">
+<div class="rack" data-rack>
   {#each visible as slot (slot.index)}
     <button
       class="tile"