feat: HVAC ductwork + DWV plumbing systems (#402)

Adds two new MEP node families (HVAC ductwork, DWV plumbing) built on a shared port-connectivity model. Co-authored by @sudhir9297.

packages/viewer/src/systems/geometry/geometry-system.tsx

@@ -64,6 +64,14 @@ export const GeometrySystem = () => {
   // shelf dirties the shelf without altering its boards.
   const builtGeometryKeyRef = useRef<Map<string, string>>(new Map())
 
+  // Re-mark every geometry-backed node dirty whenever a viewer appearance
+  // value changes, so `def.geometry` builders re-run and pick up the new
+  // shading / texture / preset / theme. These four are deliberate re-run
+  // TRIGGERS, not values read in the body — the effect re-fires on any
+  // change. They're primitives (stable by value), so listing them is safe;
+  // biome flags them as "unnecessary" because the body doesn't reference
+  // them, but dropping them silently breaks appearance-mode switching.
+  // biome-ignore lint/correctness/useExhaustiveDependencies: shading/textures/colorPreset/sceneTheme are intentional re-run triggers; removing them stops geometry from rebuilding on appearance change.
   useEffect(() => {
     const nodes = useScene.getState().nodes
     for (const node of Object.values(nodes)) {

packages/viewer/src/systems/level/level-system.tsx

@@ -1,8 +1,7 @@
-import { type LevelNode, sceneRegistry, useScene } from '@pascal-app/core'
+import { getLevelHeight, type LevelNode, sceneRegistry, useScene } from '@pascal-app/core'
 import { useFrame } from '@react-three/fiber'
 import { lerp } from 'three/src/math/MathUtils.js'
 import useViewer from '../../store/use-viewer'
-import { getLevelHeight } from './level-utils'
 
 const EXPLODED_GAP = 5
 

packages/viewer/src/systems/level/level-utils.ts

@@ -1,53 +1,4 @@
-import {
-  type CeilingNode,
-  type LevelNode,
-  sceneRegistry,
-  useScene,
-  type WallNode,
-} from '@pascal-app/core'
-
-export const DEFAULT_LEVEL_HEIGHT = 2.5
-
-// Cache: levelId → computed height. Invalidated when the nodes reference changes.
-// Zustand produces a new `nodes` object on every mutation, so reference equality
-// is a zero-cost way to detect stale data without any subscription overhead.
-const heightCache = new Map<string, number>()
-let lastNodesRef: object | null = null
-
-export function getLevelHeight(
-  levelId: string,
-  nodes: ReturnType<typeof useScene.getState>['nodes'],
-): number {
-  if (nodes !== lastNodesRef) {
-    heightCache.clear()
-    lastNodesRef = nodes
-  }
-
-  if (heightCache.has(levelId)) return heightCache.get(levelId)!
-
-  const level = nodes[levelId as LevelNode['id']] as LevelNode | undefined
-  if (!level) return DEFAULT_LEVEL_HEIGHT
-
-  let maxTop = 0
-
-  for (const childId of level.children) {
-    const child = nodes[childId as keyof typeof nodes]
-    if (!child) continue
-    if (child.type === 'ceiling') {
-      const ch = (child as CeilingNode).height ?? DEFAULT_LEVEL_HEIGHT
-      if (ch > maxTop) maxTop = ch
-    } else if (child.type === 'wall') {
-      let meshY = sceneRegistry.nodes.get(childId as any)?.position.y ?? 0
-      if (meshY < 0) meshY = 0
-      const top = meshY + ((child as WallNode).height ?? DEFAULT_LEVEL_HEIGHT)
-      if (top > maxTop) maxTop = top
-    }
-  }
-
-  const height = maxTop > 0 ? maxTop : DEFAULT_LEVEL_HEIGHT
-  heightCache.set(levelId, height)
-  return height
-}
+import { getLevelHeight, type LevelNode, sceneRegistry, useScene } from '@pascal-app/core'
 
 /**
  * Instantly snaps all level Objects3D to their true stacked Y positions