feat: add self-contained offline development resources

scripts/verify-freecad-source.mjs

@@ -1,8 +1,29 @@
 import { execFileSync } from 'node:child_process'
 import { readFile } from 'node:fs/promises'
+import { resolve } from 'node:path'
 
 const toolchain = JSON.parse(await readFile(new URL('../config/freecad-toolchain.json', import.meta.url), 'utf8'))
 const reference = `refs/tags/${toolchain.source.tag}`
+const root = resolve(new URL('..', import.meta.url).pathname)
+const source = resolve(root, toolchain.sourceCheckout.defaultDirectory)
+const git = (...args) => execFileSync('git', args, { encoding: 'utf8', timeout: 30000 }).trim()
+
+if (process.env.FREECAD_SOURCE_OFFLINE === '1') {
+  const revision = git('-C', source, 'rev-parse', 'HEAD')
+  if (revision !== toolchain.source.commit) {
+    console.error(`FreeCAD source mismatch: expected ${toolchain.source.commit}, received ${revision}.`)
+    process.exit(1)
+  }
+  const submodules = git('-C', source, 'submodule', 'status', '--recursive').split(/\r?\n/).filter(Boolean)
+  const incomplete = submodules.filter((line) => line.startsWith('-') || line.startsWith('+') || line.startsWith('U'))
+  if (submodules.length !== 4 || incomplete.length > 0) {
+    console.error(`FreeCAD offline source requires four clean initialized submodules; received ${JSON.stringify(submodules)}.`)
+    process.exit(1)
+  }
+  console.log(`FreeCAD offline source verified: ${source} @ ${revision}, submodules=${submodules.length}.`)
+  process.exit(0)
+}
+
 const output = execFileSync('git', ['ls-remote', toolchain.source.repository, reference], { encoding: 'utf8', timeout: 30000 }).trim()
 const [resolved, resolvedReference] = output.split(/\s+/)
 if (resolvedReference !== reference || resolved !== toolchain.source.commit) {