feat(editor): preset placement polish — params, move tool, shadows, isolation (#357)

* feat(editor): preset placement polish — params, move tool, shadows

- wall/slab/ceiling/roof create paths consume `toolDefaults` so template
  presets build with their saved params; cleared on tool unmount
- wall draw preview reflects the preset's height/thickness (+ HUD labels)
- box-select picks up registry-selectable kinds (shelf) via bbox
- registry + column move tools: snap to the active grid step, R/T rotation,
  and ignore the stray trailing click that armed the move (no double-place)
- shelf geometry casts + receives shadows like fence/slab

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* feat(viewer): expose isIsolationActive() for isolation-aware consumers

Tracks whether an isolation filter is currently applied and exposes it so
hosts can avoid acting on the partial view — e.g. skipping project-thumbnail
autosave while a single subtree is isolated (preset capture).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

packages/viewer/src/index.ts

@@ -37,7 +37,12 @@ export {
   SUBTRACTION,
 } from './lib/csg-utils'
 export type { EdgeMode } from './lib/edge-style'
-export { applyIsolation, clearIsolation, collectIsolationSubtree } from './lib/isolation'
+export {
+  applyIsolation,
+  clearIsolation,
+  collectIsolationSubtree,
+  isIsolationActive,
+} from './lib/isolation'
 export { GRID_LAYER, OVERLAY_LAYER, SCENE_LAYER, ZONE_LAYER } from './lib/layers'
 export {
   applyMaterialPresetToMaterials,

packages/viewer/src/lib/isolation.ts

@@ -12,6 +12,17 @@ const ORIGINAL_LAYERS = Symbol('isolation:original-layers')
 
 type IsolationCarrier = Object3D & { [ORIGINAL_LAYERS]?: number }
 
+// Whether a subtree is currently isolated (some objects have SCENE_LAYER
+// disabled). Read by consumers that must not act on the partial view — e.g.
+// the project-thumbnail autosave skips capturing while isolated so it never
+// snapshots a single focused item as the whole project's thumbnail.
+let isolationActive = false
+
+/** True while an isolation filter is applied (see {@link applyIsolation}). */
+export function isIsolationActive(): boolean {
+  return isolationActive
+}
+
 /**
  * Compute the union of every isolated subtree's `Object3D` descendants.
  *
@@ -71,6 +82,7 @@ export function applyIsolation(ids: ReadonlyArray<AnyNodeId> | null): void {
     if (keep.has(obj)) continue
     hideRecursive(obj, keep)
   }
+  isolationActive = true
 }
 
 function hideRecursive(obj: Object3D, keep: Set<Object3D>): void {
@@ -98,4 +110,5 @@ export function clearIsolation(): void {
       }
     })
   }
+  isolationActive = false
 }