feat: establish facade-first runtime boundary

scripts/check-facade-boundary.mjs

@@ -0,0 +1,34 @@
+import { readdir, readFile } from 'node:fs/promises'
+import { join } from 'node:path'
+
+const sourceRoot = new URL('../src/', import.meta.url)
+const forbidden = [
+  /from\s+["']three(?:\/|["'])/, /from\s+["']@types\/three/, /from\s+["']sqlite3?/, /from\s+["']@sqlite/, /from\s+["']opfs/, /SharedArrayBuffer/, /\bpostMessage\s*\(/,
+]
+const allowDirectRuntime = new Set(['facade/threeViewport.ts', 'facade/threeViewport.tsx', 'facade/persistenceWorker.ts', 'facade/geometryWorker.ts'])
+
+async function walk(relative = '') {
+  const directory = new URL(relative, sourceRoot)
+  const entries = await readdir(directory, { withFileTypes: true })
+  const files = []
+  for (const entry of entries) {
+    const next = join(relative, entry.name)
+    if (entry.isDirectory()) files.push(...await walk(next))
+    else if (/\.(ts|tsx)$/.test(entry.name)) files.push(next)
+  }
+  return files
+}
+
+const violations = []
+for (const file of await walk()) {
+  if (allowDirectRuntime.has(file)) continue
+  const content = await readFile(new URL(file, sourceRoot), 'utf8')
+  for (const pattern of forbidden) if (pattern.test(content)) violations.push(`${file}: ${pattern}`)
+}
+
+if (violations.length) {
+  console.error('Facade-only boundary failed:')
+  violations.forEach((violation) => console.error(`- ${violation}`))
+  process.exit(1)
+}
+console.log(`Facade-only boundary passed (${(await walk()).length} TypeScript source files checked).`)