Drop wall + fence feature flags: register unconditionally; remove verification logs

Parity comparison against deployed prod is now cleaner than juggling
env-var flag toggles locally. Both kinds enter builtinPlugin.nodes
unconditionally; the Phase 0 dispatch shims (<LegacySystem kind="X">
wrappers + NodeRenderer's registry-first branch) handle the cutover.

Files deleted:
 - packages/nodes/src/wall/feature-flag.ts
 - packages/nodes/src/fence/feature-flag.ts

Files changed:
 - packages/nodes/src/index.ts: drops isWallRegistryEnabled /
   isFenceRegistryEnabled gates; wallDefinition + fenceDefinition
   land directly in builtinPlugin.nodes.
 - packages/nodes/src/{wall,fence}/index.ts: drop the flag re-export.
 - packages/nodes/src/{wall,fence}/renderer.tsx: drop the one-shot
   verification console.info. Same for the system.tsx wrappers.
 - packages/viewer/src/components/renderers/{wall,fence}/{wall,fence}-
   renderer.tsx: drop the paired [X:legacy] verification logs (no
   longer comparing flag-toggled paths).

Net DX: no env var to remember when starting `bun dev:community`. To
A/B test, compare against editor.pascal.app deployed prod.

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

packages/viewer/src/components/renderers/fence/fence-renderer.tsx

@@ -1,15 +1,9 @@
 import { type FenceNode, useRegistry, useScene } from '@pascal-app/core'
-import { useEffect, useLayoutEffect, useMemo, useRef } from 'react'
+import { useLayoutEffect, useMemo, useRef } from 'react'
 import type { Mesh } from 'three'
 import { useNodeEvents } from '../../../hooks/use-node-events'
 import { DEFAULT_STAIR_MATERIAL } from '../../../lib/materials'
 
-// Phase 5 verification log — see matching `[fence:registry]` log in
-// nodes/src/fence/renderer.tsx. Fires once if the legacy path is active
-// (flag off or kind not registered). Drop alongside the legacy file at
-// Phase 6 cleanup.
-let didLogFirstLegacyFenceMount = false
-
 export const FenceRenderer = ({ node }: { node: FenceNode }) => {
   const ref = useRef<Mesh>(null!)
   const handlers = useNodeEvents(node, 'fence')
@@ -20,14 +14,6 @@ export const FenceRenderer = ({ node }: { node: FenceNode }) => {
     useScene.getState().markDirty(node.id)
   }, [node.id])
 
-  useEffect(() => {
-    if (didLogFirstLegacyFenceMount) return
-    didLogFirstLegacyFenceMount = true
-    console.info(
-      '[fence:legacy] first legacy FenceRenderer mounted — registry-driven FenceRenderer is NOT in use',
-    )
-  }, [])
-
   return (
     <mesh
       castShadow

packages/viewer/src/components/renderers/wall/wall-renderer.tsx

@@ -5,12 +5,6 @@ import { useNodeEvents } from '../../../hooks/use-node-events'
 import { getVisibleWallMaterials } from '../../../systems/wall/wall-materials'
 import { NodeRenderer } from '../node-renderer'
 
-// Phase 3 verification — see the matching `[wall:registry]` log in
-// nodes/src/wall/renderer.tsx. When this fires, wall is on the legacy
-// path; the registry-driven WallRenderer is not in use. Drop alongside
-// the legacy file at Phase 6.
-let didLogFirstLegacyWallMount = false
-
 function createEmptyWallGeometry() {
   const geometry = new BufferGeometry()
   geometry.setAttribute('position', new Float32BufferAttribute([], 3))
@@ -35,14 +29,6 @@ export const WallRenderer = ({ node }: { node: WallNode }) => {
     useScene.getState().markDirty(node.id)
   }, [node.id])
 
-  useEffect(() => {
-    if (didLogFirstLegacyWallMount) return
-    didLogFirstLegacyWallMount = true
-    console.info(
-      '[wall:legacy] first legacy WallRenderer mounted — registry-driven WallRenderer is NOT in use',
-    )
-  }, [])
-
   useEffect(() => {
     return () => {
       placeholderGeometry.dispose()