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/box-vent/preview.tsx

@@ -17,6 +17,7 @@ import type { BoxVentNode } from './schema'
  * the cursor ray and starve the placement tool of `roof:move` events.
  */
 const BoxVentPreview = ({ node, invalid }: { node: BoxVentNode; invalid?: boolean }) => {
+  // biome-ignore lint/correctness/useExhaustiveDependencies: deps deliberately list the build inputs; depending on the whole object would rebuild on unrelated field changes.
   const geometry = useMemo(
     () => buildBoxVentGeometry(node),
     [node.width, node.depth, node.height, node.hoodOverhang, node.style],

packages/nodes/src/box-vent/renderer.tsx

@@ -75,6 +75,7 @@ const BoxVentRenderer = ({ node: storeNode }: { node: BoxVentNode }) => {
   // every parametric field, including the per-style ones. Listing them
   // explicitly keeps the dep array tight (vs. `[node]` which would
   // also fire on `name` / `visible` flips).
+  // biome-ignore lint/correctness/useExhaustiveDependencies: deps deliberately list the build inputs; depending on the whole object would rebuild on unrelated field changes.
   const geometry = useMemo(
     () => buildBoxVentGeometry(node),
     [