Run a long-running command in a Vercel Sandbox in detached mode and stream its stdout/stderr in real time.

Documented steps

1. Create a sandbox with a timeout long enough for the task: `const sandbox = await Sandbox.create({ timeout: 120_000 })` (milliseconds). Docs: https://vercel.com/docs/sandbox/working-with-sandbox#execute-long-running-tasks
2. Launch the command detached so it returns immediately: `const command = await sandbox.runCommand({ cmd: 'bash', args: ['-lc', 'for i in 1 2 3; do echo $i; sleep 1; done'], detached: true })`. In Python use `command = await sandbox.run_command_detached('bash', [...])`.
3. Stream log entries as they arrive: `for await (const line of command.logs()) { if (line.stream === 'stdout') process.stdout.write(line.data); else process.stderr.write(line.data); }`. Each entry has `{ stream: 'stdout'|'stderr', data: string }`.
4. Wait for completion and get the final result: `const finished = await command.wait(); console.log(finished.exitCode);`.
5. Store `command.cmdId` if you need to reattach to this command later (e.g. from another process) via `sandbox.getCommand(cmdId)`.
6. Stop the sandbox with `await sandbox.stop()` once the detached process and any follow-up work is complete.