feat(editor): placement-time + resize-time opening guides

Extend the opening proximity guides to two more interactions:

  - PLACEMENT: the door/window placement tools publish the same 3D guides
    (sill/head, edge proximity, sill alignment, equal-spacing) while a NEW
    opening is being dropped; window placement also snaps its sill to a
    neighbour's sill/centre/top (Shift bypass) — so "two windows aligned" reads
    during placement, not just move.
  - RESIZE: a new `onDrag` hook on the linear-resize handle descriptor lets the
    door/window width/height arrows publish live guides for the edge being
    resized — proximity to neighbours as the width grows, and the live sill/head
    as a window's height changes. The generic LinearArrow stays kind-agnostic;
    only door/window declare the hook.

Refactor (Codex review follow-up): one `publishOpeningGuidesForWallEvent`
wrapper now backs all four wall-event publish sites (door/window move +
placement) over a shared `makeWallToWorld`; window placement's repeated
sill-snap is a single `resolvePlacementY` helper. Opening guides clear on
commit / leave / cancel / roof-hover / unmount (mirroring the alignment-guide
lifecycle) and on resize end.

Codex-reviewed — no blockers; lifecycle/leaks, coordinate frame, sill-snap
precedence, and resize disposal confirmed. Typecheck + biome + 23 core + 170
nodes tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/core/src/registry/handles.ts

@@ -116,6 +116,14 @@ export type LinearResizeHandle<N> = {
   anchor: HandleAnchor
   currentValue: (node: N) => number
   apply: (node: N, newValue: number, sceneApi: SceneApi) => Partial<N>
+  /**
+   * Optional per-tick hook fired while this handle is being dragged, with the
+   * live (in-progress, override-merged) node. A pure side-channel for transient
+   * feedback — doors/windows use it to publish proximity / sill guides for the
+   * edge being resized. The return value is ignored; the resize itself is driven
+   * by `apply`.
+   */
+  onDrag?: (node: N, sceneApi: SceneApi) => void
   /**
    * Cross-node redirect. By default the drag's live override + the
    * committed write both land on the SELECTED node. When this returns