feat(editor): mode-driven shelf/column/spawn placement + cross-kind floor collision

Migrate the remaining floor-placed kinds onto the unified snapping/modifier
model and generalize floor collision so any solid floor kind blocks any other.

- shelf/column/spawn declare `snapProfile: 'item'` → contextual snapping chip,
  Shift=cycle, Ctrl=grid step during placement; their tools read the active
  mode (grid/lines/off) instead of legacy Shift/Alt bypass; spawn fresh
  placement now respects alignment ("lines") like its move.
- Resize/radial handles claim the handle-drag scope (new RESIZE_HANDLE_DRAG_LABEL)
  so the HUD shows no select-mode shortcuts mid-resize.
- Column move migrated to the generic MoveRegistryNodeTool (declare `movable`,
  drop the bespoke move-tool) — gains mode-driven snapping, alignment, R/T,
  slab lift, grid SFX, and the collision box for free. 2D move still routes
  through `floorplanMoveTarget`.
- Cross-kind floor collision: new declarative `FloorPlacedConfig.collides`
  (item/shelf/column opt in; spawn/MEP/stair stay off). `canPlaceOnFloor` now
  treats every colliding floor kind as an obstacle (was item-only), reading the
  declarative footprint; the generic move tool's red/green placement box gates
  on `collides`. Column footprint uses the visible `columnFootprintHalf` extent
  so the box/slab-lift/collision track the real (round/square) column size.

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

packages/nodes/src/column/tool.tsx

@@ -11,6 +11,8 @@ import {
 } from '@pascal-app/core'
 import {
   getFloorStackPreviewPosition,
+  isGridSnapActive,
+  isMagneticSnapActive,
   triggerSFX,
   useAlignmentGuides,
   useEditor,
@@ -87,8 +89,8 @@ const ColumnTool = () => {
         rawZ: event.localPosition[2],
         gridStep: useEditor.getState().gridSnapStep,
         candidates: alignmentCandidates,
-        bypassAlignment: event.nativeEvent?.altKey === true || event.nativeEvent?.shiftKey === true,
-        bypassGrid: event.nativeEvent?.shiftKey === true,
+        bypassAlignment: !isMagneticSnapActive(),
+        bypassGrid: !isGridSnapActive(),
       })
       useAlignmentGuides.getState().set(guides)
 
@@ -108,10 +110,7 @@ const ColumnTool = () => {
       usePlacementPreview.getState().set({ ...previewNode, position })
 
       const prev = previousSnapRef.current
-      if (
-        event.nativeEvent?.shiftKey !== true &&
-        (!prev || prev[0] !== position[0] || prev[1] !== position[2])
-      ) {
+      if (!prev || prev[0] !== position[0] || prev[1] !== position[2]) {
         triggerSFX('sfx:grid-snap')
         previousSnapRef.current = [position[0], position[2]]
       }
@@ -124,7 +123,7 @@ const ColumnTool = () => {
           activeLevelId,
           event,
           useEditor.getState().gridSnapStep,
-          event.nativeEvent?.shiftKey === true,
+          !isGridSnapActive(),
         )
 
       const column = createColumnFromPreset(DEFAULT_COLUMN_PRESET_ID, position)