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,