feat: add self-contained offline development resources

scripts/build-opencamlib-wasm.mjs

@@ -1,5 +1,5 @@
 import { execFileSync } from 'node:child_process'
-import { cp, mkdir, readFile, rm, writeFile } from 'node:fs/promises'
+import { access, cp, mkdir, readFile, rm, writeFile } from 'node:fs/promises'
 import { resolve } from 'node:path'
 
 const root = resolve(new URL('..', import.meta.url).pathname)
@@ -7,11 +7,15 @@ const source = resolve(root, 'OpenCAMLib')
 const build = resolve(root, '.cache/opencamlib-wasm')
 const boost = resolve(root, '.cache/opencamlib-boost')
 const install = resolve(root, 'public/vendor/opencamlib')
+const offlineBoost = resolve(root, '.cache/offline-sysroot/include/boost')
+const systemBoost = process.env.BOOST_INCLUDE_DIR
+  ? resolve(process.env.BOOST_INCLUDE_DIR, 'boost')
+  : '/usr/include/boost'
 const revision = execFileSync('git', ['-C', source, 'rev-parse', 'HEAD'], { encoding: 'utf8' }).trim()
 
 await rm(boost, { recursive: true, force: true })
 await mkdir(boost, { recursive: true })
-await cp('/usr/include/boost', resolve(boost, 'boost'), { recursive: true })
+await cp(await access(offlineBoost).then(() => offlineBoost, () => systemBoost), resolve(boost, 'boost'), { recursive: true })
 await mkdir(build, { recursive: true })
 
 const configure = [