chore(scripts): add parallel build scripts

Replace sequential `npm run build --workspaces --if-present` with
concurrent execution via a reusable `parallelTask` utility. Full
`npm run build` now runs cleanup then all 7 build tasks in parallel.

scripts/parallel-task.js

@@ -0,0 +1,115 @@
+import chalk from 'chalk'
+import { spawn } from 'child_process'
+
+/**
+ * Run multiple shell commands in parallel with progress reporting.
+ *
+ * @param {{ label: string, command: string, cwd?: string }[]} tasks
+ * @param {{ timeoutMs?: number }} options - Default timeout 30s per task
+ * @returns {Promise<void>} Rejects (process.exit) if any task fails
+ */
+export async function parallelTask(tasks, options = {}) {
+	const { timeoutMs = 30_000 } = options
+	const total = tasks.length
+
+	const bgColors = [
+		chalk.bgCyan,
+		chalk.bgMagenta,
+		chalk.bgBlue,
+		chalk.bgYellow,
+		chalk.bgGreenBright,
+	]
+	const fgOnBg = [chalk.black, chalk.white, chalk.white, chalk.black, chalk.black]
+
+	let done = 0
+	let failed = 0
+
+	const spinner = ['◐', '◓', '◑', '◒']
+	let tick = 0
+
+	const printProgress = () => {
+		const running = total - done - failed
+		const s = spinner[tick++ % spinner.length]
+		const status = failed
+			? `${running} running, ${done} done, ${chalk.bgRed.white.bold(` ${failed} failed `)}`
+			: `${running} running, ${done} done`
+		process.stderr.write(`\r${chalk.bgCyan.black.bold(` ${s} ${done}/${total} `)} ${status}  `)
+	}
+
+	const timer = setInterval(printProgress, 1000)
+	printProgress()
+
+	/** @type {{ label: string, output: string, exitCode: number | null, timedOut: boolean }[]} */
+	const results = await Promise.all(
+		tasks.map(
+			(task) =>
+				new Promise((resolve) => {
+					const chunks = /** @type {Buffer[]} */ ([])
+
+					const child = spawn('sh', ['-c', task.command], {
+						cwd: task.cwd,
+						env: { ...process.env, FORCE_COLOR: '1', NO_COLOR: '' },
+						stdio: ['ignore', 'pipe', 'pipe'],
+					})
+
+					child.stdout.on('data', (d) => chunks.push(d))
+					child.stderr.on('data', (d) => chunks.push(d))
+
+					const timeout = setTimeout(() => {
+						child.kill('SIGTERM')
+					}, timeoutMs)
+
+					child.on('close', (code, signal) => {
+						clearTimeout(timeout)
+						const timedOut = signal === 'SIGTERM'
+						const exitCode = timedOut ? 1 : code
+
+						if (exitCode === 0) done++
+						else failed++
+
+						resolve({
+							label: task.label,
+							output: Buffer.concat(chunks).toString(),
+							exitCode,
+							timedOut,
+						})
+					})
+				})
+		)
+	)
+
+	clearInterval(timer)
+	process.stderr.write('\r\x1b[K')
+
+	const failedTasks = /** @type {typeof results} */ ([])
+
+	for (let i = 0; i < results.length; i++) {
+		const r = results[i]
+		if (r.exitCode !== 0) {
+			failedTasks.push(r)
+			continue
+		}
+		const bg = bgColors[i % bgColors.length]
+		const fg = fgOnBg[i % fgOnBg.length]
+		const banner = bg(fg.bold(` ✔ ${r.label} `))
+		console.log(`\n${banner}`)
+		if (r.output.trim()) process.stdout.write(r.output)
+	}
+
+	if (failedTasks.length) {
+		for (const r of failedTasks) {
+			const banner = chalk.bgRed(
+				chalk.white.bold(` ✘ ${r.label} ${r.timedOut ? '· timed out' : '· failed'} `)
+			)
+			console.log(`\n${banner}`)
+			if (r.output.trim()) process.stdout.write(r.output)
+		}
+		const summary = failedTasks.map((t) => t.label).join(', ')
+		console.error(
+			`\n${chalk.bgRed.white.bold(` ✘ ${failedTasks.length}/${total} failed: ${summary} `)}`
+		)
+		process.exit(1)
+	}
+
+	console.log(`\n${chalk.bgGreen.black.bold(` ✔ All ${total} tasks completed `)}`)
+}