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/nodes/src/dormer/csg-geometry.ts

@@ -325,7 +325,6 @@ export function generateDormerGeometry(
 
   const dormerBrushes = getRoofSegmentBrushes(virtualSegment)
   if (!dormerBrushes) {
-    // biome-ignore lint/suspicious/noConsole: keep diagnostic — fallback path.
     console.warn('[dormer] getRoofSegmentBrushes returned null; using fallback silhouette.')
     return buildDormerFallbackGeometry(dormer)
   }
@@ -472,7 +471,6 @@ export function generateDormerGeometry(
     remapRoofShellFaces(resultGeo, virtualSegment)
     splitDormerGableMaterial(resultGeo, dormer.height, DORMER_GABLE_MATERIAL_INDEX)
   } catch (e) {
-    // biome-ignore lint/suspicious/noConsole: dormer CSG can throw; keep diagnostic.
     console.error('[dormer] CSG failed, falling back to silhouette:', e)
     if (dormerSolid) {
       try {
@@ -492,7 +490,6 @@ export function generateDormerGeometry(
   // dormer is at least visible.
   const triCount = resultGeo.getIndex()?.count ?? resultGeo.getAttribute('position')?.count ?? 0
   if (triCount === 0) {
-    // biome-ignore lint/suspicious/noConsole: keep diagnostic — empty CSG.
     console.warn('[dormer] CSG produced empty geometry; using fallback silhouette.')
     return buildDormerFallbackGeometry(dormer)
   }