fix(editor): preserve grab offset when moving items (no teleport-to-cursor) (#416)

* fix(editor): preserve grab offset when moving items (no teleport-to-cursor)

Grabbing a placed item to move it (move-cross handle or the Move
affordance) snapped the item's origin to the cursor instead of keeping
the offset between the grab point and the origin.

- Floor (regression): the grab-offset rewrite patched event.localPosition,
  but floorStrategy.move reads event.position (the world cursor) for its
  world-grid snap on the default non-Shift path -- a read added after the
  offset fix landed. Now also correct event.position, derived from the
  corrected building-local point via buildingLocalToWorld.
- Wall / ceiling / item-surface / shelf: the shared surface strategies
  snapped the origin straight to the cursor with no grab offset. Added
  per-surface grab anchors (start + (raw - anchor)) seeded on the first
  move per host and reset on leave/detach; host-resting items start in
  their surface, and the level-reparent effect skips intentionally-hosted
  drafts so the dragged mesh stays on its host.

Rename preserveFloorDragOffset -> preserveDragOffset (it now governs all
surfaces). 2D move paths already preserved the grab offset, so no sibling
change is needed -- this brings 3D into parity.

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

* refactor(editor): tidy grab-offset floor/wall paths (quality pass)

Behaviour-preserving readability pass before shipping:
- Extract the floor grab-offset IIFE into a named `applyFloorGrabOffset`
  helper (parity with `resolveHostSurfaceWorld`); drop redundant tuple
  casts via the return annotation and tighten the comment.
- Wall move: always set `position` (raw hit when the wall mesh is absent)
  instead of a conditional object spread.

A reviewed dedup of the three per-surface anchors was deliberately NOT
taken — the wall (X/Y) / ceiling (X/Z) / host-surface frames are
heterogeneous enough that unifying them adds more indirection than it
removes.

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

---------

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

packages/nodes/src/item/move-tool.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import type { ItemNode } from '@pascal-app/core'
+import { type AnyNodeId, type ItemNode, useScene } from '@pascal-app/core'
 import {
   type PlacementState,
   triggerSFX,
@@ -67,6 +67,32 @@ function getInitialState(node: ItemNode): PlacementState {
       shelfId: null,
     }
   }
+  // A floor item resting on a host surface (table / counter / shelf) starts in
+  // that surface, not 'floor', so the first pointer move runs the surface move
+  // handler — which preserves the grab offset — instead of a fresh `enter()`
+  // that snaps the item's origin under the cursor. Without this the item
+  // teleports the instant it's grabbed.
+  const parent = node.parentId ? useScene.getState().nodes[node.parentId as AnyNodeId] : undefined
+  if (parent?.type === 'item') {
+    return {
+      surface: 'item-surface',
+      wallId: null,
+      roofSegmentId: null,
+      ceilingId: null,
+      surfaceItemId: node.parentId,
+      shelfId: null,
+    }
+  }
+  if (parent?.type === 'shelf') {
+    return {
+      surface: 'shelf-surface',
+      wallId: null,
+      roofSegmentId: null,
+      ceilingId: null,
+      surfaceItemId: null,
+      shelfId: node.parentId,
+    }
+  }
   return {
     surface: 'floor',
     wallId: null,
@@ -102,7 +128,7 @@ export function MoveItemTool({ node }: { node: ItemNode }) {
       : getInitialState(node),
     // Preserve the original item's scale so Y-position calculations use the correct height.
     defaultScale: isNew ? node.scale : undefined,
-    preserveFloorDragOffset: true,
+    preserveDragOffset: true,
     initDraft: (gridPosition) => {
       if (isNew) {
         // Duplicate: floor items get a draft immediately; wall/ceiling