01 (high): the live resize preview no longer touches _serverCfg — it lives in
the _rszPreview overlay served to renders via _curSpaceCfg/_renderCfg, so a
debounced write queued from a previous edit can never carry mid-drag geometry
to the server; commit happens once, on pointerup; Esc just drops the overlay.
03: pointercancel/lostpointercapture take the cancel path (no commit, no undo
step, no write) for edge and corner handles alike.
04: in the resize tool the wall handles own the hit test — the transparent
.op-hit is inert and the resize layer renders above the openings; a door at a
wall midpoint no longer shadows the handle, other tools unchanged.
02: the 30 cm floor is orientation-independent — minSpanClearance (band sweep
of the moved stretch) for wall drags, minPolyWidth (calipers) for the scale
frame; already-thin rooms may improve, never worsen.
Matysh