feat: IFC → Pascal converter (package + app)

Brings the IFC-to-Pascal converter into the monorepo as a pure-logic
package plus a Next.js app, replacing the standalone repo that consumed
published @pascal-app/* packages (and drifted from their schemas).

packages/ifc-converter — pure conversion. Parses IFC via web-ifc and
maps elements onto @pascal-app/core node schemas (workspace-linked, so
no more version drift). Builds doors/windows, walls, slabs, columns,
roofs, stairs, sites/buildings/levels. Validates each node via the real
Zod schemas at build time (tryParse) and strips undefined metadata.

apps/ifc-converter — the UI: drop zone, example picker, element search,
JSON download, and a 3D preview rendered through the real
@pascal-app/viewer (registry bootstrap + read-only scene) with a custom
toolbar (camera/level/wall/grid/theme), level selector with
camera-focus, auto-fit, and selection bridged to an inspector.

Conversion specifics worth noting:
- Door/window vertical centering (height/2; windows + sill).
- Nearest-wall hosting fallback for files lacking IFCRELFILLSELEMENT,
  preferring walls long enough to contain the opening and clamping the
  along-wall position so cutouts can't overflow and break wall CSG.
- Plain IFCWALL (Brep/mapped geometry) falls back to default
  height/thickness instead of collapsing to zero-height slivers.
- Columns convert as plain structural shafts (no decorative
  base/capital) sized from the IFC profile.
- Beams + items are skipped for now (no Pascal beam type; items need a
  catalog asset) — counted in the conversion summary.

Large example IFCs are fetched from a public bucket at runtime; the four
small ones are committed. web-ifc.wasm is copied into public/ on
install/dev/build. README flags early-alpha + invites contributions.

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

apps/ifc-converter/lib/bootstrap.ts

@@ -0,0 +1,24 @@
+import { type AnyNodeDefinition, nodeRegistry, registerNode } from '@pascal-app/core'
+import { builtinPlugin } from '@pascal-app/nodes'
+
+// Mirrors apps/editor/lib/bootstrap.ts — registers every built-in node
+// kind synchronously so the registry is populated before the first
+// `<Viewer>` mounts. Without this every NodeRenderer resolves to null
+// and the preview is empty. HMR-safe via the closure-scoped flag.
+let builtinsLoaded = false
+
+export function loadBuiltins(): void {
+  if (builtinsLoaded) return
+  builtinsLoaded = true
+  for (const def of builtinPlugin.nodes ?? []) {
+    registerNode(def as AnyNodeDefinition)
+  }
+  if (typeof console !== 'undefined') {
+    const kinds = Array.from(nodeRegistry.entries(), ([k]) => k)
+    console.info(
+      `[pascal:registry] loaded ${builtinPlugin.id} v${builtinPlugin.apiVersion} (${kinds.length} kinds)`,
+    )
+  }
+}
+
+loadBuiltins()