add builder and updater

scripts/package.mjs

@@ -0,0 +1,26 @@
+import { build, Platform, Arch } from 'electron-builder'
+import { rm } from 'node:fs/promises'
+import { createBuildConfig } from '../build/config.mjs'
+import { writeReleaseManifest } from './releaseArtifacts.mjs'
+
+const args = process.argv.slice(2)
+if (args.some((arg) => !['--release', '--dir'].includes(arg))) {
+  throw new Error('Usage: node scripts/package.mjs [--release] [--dir]')
+}
+const release = args.includes('--release')
+if (release && args.includes('--dir')) throw new Error('Release builds must produce an installer.')
+// Never let a failed rebuild leave an older directory looking publishable.
+if (release) {
+  await rm('dist/release/release-ready.json', { force: true })
+} else {
+  process.env.CSC_IDENTITY_AUTO_DISCOVERY = 'false'
+}
+const config = createBuildConfig({ release })
+await build({
+  config,
+  targets: Platform.WINDOWS.createTarget(args.includes('--dir') ? ['dir'] : ['nsis'], Arch.x64),
+  publish: 'never'
+})
+if (release) {
+  await writeReleaseManifest(config.directories.output, config.publish[0].url)
+}