feat(editor): node-declared per-context snapping + contextual HUD + painter scope

Generify the snapping/modifier HUD off the FSM scope and node declarations
instead of wall-creation-shaped, leaking pills.

- Per-context snapping (`snappingModeByContext`, persisted): wall / item /
  polygon mode-sets with exclusive modes (grid | lines | angles | off), each
  doing exactly what its chip says. Context is node-declared via the new
  `NodeDefinition.snapProfile` ('item' | 'structural'); the resolver maps
  (profile × action) → context with no per-kind switch.
- Scope-driven HUD: helper-manager reads the interaction scope; reshaping
  (endpoint/curve/boundary) and item move get their own chip, no select-hint
  leak. Rotate R/T rounds to 45°; Alt = force-place only (hidden for
  structural kinds); Shift = cycle everywhere.
- Slab/ceiling drafting: Shift=cycle, mode-aware grid/angle, Enter finishes
  (minDraftVertices); polygon boundary vertex/edge drag begins a reshaping
  scope. Fix grid/angle being ignored on boundary edit + slab creation:
  make resolveSurfacePlanPointSnap exclusive (alignment gated on magnetic) so
  grid/angles keep the snapped fallback instead of the raw cursor.
- Painter application scope: node-derived (single/object/matching/room) from
  the hovered node, cyclable via Shift, single-source HUD chip.
- Remove the redundant GridSnapControl from view-toggles (grid step lives in
  the contextual HUD now).

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

packages/nodes/src/ceiling/boundary-editor.tsx

@@ -2,11 +2,13 @@
 
 import { type CeilingNode, resolveLevelId, useLiveNodeOverrides, useScene } from '@pascal-app/core'
 import {
+  boundaryReshapeScope,
   clearCeilingSnapFeedback,
   PolygonEditor,
   type PolygonEditorPlanPointSnapContext,
   resolveCeilingPlanPointSnap,
   triggerSFX,
+  useInteractionScope,
 } from '@pascal-app/editor'
 import { useViewer } from '@pascal-app/viewer'
 import { useCallback, useEffect, useMemo, useRef } from 'react'
@@ -95,13 +97,19 @@ export const CeilingBoundaryEditor: React.FC<{ ceilingId: CeilingNode['id'] }> =
 
   const handleDragStateChange = useCallback(
     (isDragging: boolean) => {
-      if (!isDragging) {
+      // A vertex/edge drag is a `boundary` reshape — drive the snapping HUD
+      // (no-angle 'polygon' set) and keep the idle select hints off-screen.
+      const scope = useInteractionScope.getState()
+      if (isDragging) {
+        scope.begin(boundaryReshapeScope(ceilingId))
+      } else {
+        scope.endIf((s) => s.kind === 'reshaping' && s.reshape === 'boundary')
         ownsPolygonPreviewRef.current = false
         clearCeilingSnapFeedback()
       }
       setCeilingHandleHover(isDragging)
     },
-    [setCeilingHandleHover],
+    [ceilingId, setCeilingHandleHover],
   )
 
   const handlePolygonEditorDragCommit = useCallback(() => {
@@ -126,7 +134,6 @@ export const CeilingBoundaryEditor: React.FC<{ ceilingId: CeilingNode['id'] }> =
         levelId: ceilingLevelId,
         excludeId: ceilingId,
         altKey: context.nativeEvent?.altKey === true,
-        shiftKey: context.nativeEvent?.shiftKey === true,
       }).point,
     [ceilingId, ceilingLevelId],
   )
@@ -136,6 +143,9 @@ export const CeilingBoundaryEditor: React.FC<{ ceilingId: CeilingNode['id'] }> =
       clearCeilingSnapFeedback()
       useLiveNodeOverrides.getState().clear(ceilingId)
       useScene.getState().markDirty(ceilingId)
+      useInteractionScope
+        .getState()
+        .endIf((s) => s.kind === 'reshaping' && s.reshape === 'boundary')
       ownsPolygonPreviewRef.current = false
       if (ownsCeilingHoverRef.current && useViewer.getState().hoveredId === ceilingId) {
         useViewer.getState().setHoveredId(null)