SelectionManager: route item to furnish phase before registry fallback

User report: items needed a double click to select after the item kind
registered (Phase 5). Root cause: `getSelectionTarget` checked
`isRegistrySelectable(node.type)` as part of the FIRST branch (which
routes to structure phase), matching `item` before the item-specific
branch below could route door/window-category items to structure +
everything else to furnish.

Effect: clicking an item triggered phase switch (structure ← furnish),
then the next click selected. Hence the double click.

Fix:
 1. Item-specific case moved to the TOP of getSelectionTarget. Its
    asset.category-driven routing (door/window items → structure;
    everything else → furnish) beats any generic registry fallback.
 2. Generic registry fallback at the bottom now reads `def.category`
    to pick the phase — `category: 'furnish'` → furnish phase,
    everything else → structure/elements. Future furnish-category
    kinds (only shelf right now) route correctly without a special
    case.
 3. `isRegistrySelectable(node.type)` clause removed from the
    structure branch — replaced by the def.category check at the
    bottom.

Net: single-click selection works for items again, and the routing
logic is now cleanly capability/category-driven instead of "all
registered kinds → structure" which was a Stage A simplification
that broke as soon as a furnish-category kind registered.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/editor/src/components/editor/selection-manager.tsx

@@ -11,6 +11,7 @@ import {
   type ItemNode,
   isRegistrySelectable,
   type NodeEvent,
+  nodeRegistry,
   type RoofEvent,
   type RoofNode,
   type RoofSegmentEvent,
@@ -691,6 +692,25 @@ const SELECTION_STRATEGIES: Record<string, SelectionStrategy> = {
 }
 
 const getSelectionTarget = (node: AnyNode): SelectionTarget | null => {
+  // Item is checked FIRST so its asset.category-driven routing (door/
+  // window items land in structure phase, everything else in furnish)
+  // beats the generic registry fallback below. Without this, registering
+  // `item` (Phase 5) made isRegistrySelectable('item') match the
+  // structure branch first, breaking single-click selection: first click
+  // switched the editor to structure phase, second click selected.
+  if (node.type === 'item') {
+    const item = node as ItemNode
+    if (item.asset.category === 'door' || item.asset.category === 'window') {
+      return {
+        phase: 'structure',
+        structureLayer: 'elements',
+      }
+    }
+    return {
+      phase: 'furnish',
+    }
+  }
+
   if (node.type === 'zone') {
     return {
       phase: 'structure',
@@ -711,10 +731,7 @@ const getSelectionTarget = (node: AnyNode): SelectionTarget | null => {
     node.type === 'stair-segment' ||
     node.type === 'spawn' ||
     node.type === 'window' ||
-    node.type === 'door' ||
-    // Registry-driven kinds default to structure/elements (Phase 4 reads
-    // `definition.presentation.paletteSection` to route correctly).
-    isRegistrySelectable(node.type)
+    node.type === 'door'
   ) {
     return {
       phase: 'structure',
@@ -722,18 +739,16 @@ const getSelectionTarget = (node: AnyNode): SelectionTarget | null => {
     }
   }
 
-  if (node.type === 'item') {
-    const item = node as ItemNode
-    if (item.asset.category === 'door' || item.asset.category === 'window') {
-      return {
-        phase: 'structure',
-        structureLayer: 'elements',
-      }
-    }
-
-    return {
-      phase: 'furnish',
+  // Registry-driven kinds (Phase 5+): route by `def.category`. Built-ins
+  // above match before this fallback. Furnish-category kinds (shelf,
+  // item — already handled above) land on the furnish phase; structure-
+  // category kinds (everything else) on structure/elements.
+  const def = nodeRegistry.get(node.type)
+  if (def) {
+    if (def.category === 'furnish') {
+      return { phase: 'furnish' }
     }
+    return { phase: 'structure', structureLayer: 'elements' }
   }
 
   return null