The legacy CurveFenceTool ignored grid:click for 150ms after mount —
otherwise the very click that activates a tool (e.g. the floating menu
"curve" button) cascades through the R3F drei <Html> portal into the
grid, fires grid:click on the just-mounted tool, and commits the drag
before any preview move runs. The new useDragAction was missing this
guard, so the Stage D fence curve port "click → place sfx → exit"
without ever letting the user adjust.
Adds `activationGraceMs` (default 150) on useDragAction; ports the
sfx:item-place commit emission into FenceCurveTool so the kind-owned
tool matches legacy UX. Same guard will cover the upcoming Stage D
ports (endpoint move, whole-fence move, placement, plus
slab/ceiling/wall D).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
