fix: queue option ignored when group is not set

[seth-shi]

Bug

When enqueuing a task with a custom queue option but no group, the queue is silently ignored and the task always goes to the default queue.

Reproduction:

const client = new AsynqClient("redis://localhost:6379");
const task = new Task("email:send", { userId: 1 });

// Expected: enqueued to "critical" queue
// Actual: enqueued to "default" queue
await client.enqueue(task, { queue: "critical" });

Root Cause

In composeOptions, the queue assignment was nested inside the if (opts?.group) block:

// before (buggy)
if (opts?.group) {
  const qname = opts.queue || "";
  base.validateQueueName(qname);
  res.queue = qname;  // only runs when group is set!
}

Fix

Move queue handling into its own independent block, separate from group:

// after
if (opts?.queue) {
  base.validateQueueName(opts.queue);
  res.queue = opts.queue;
}

if (opts?.group) {
  if (opts.group.trim().length === 0) {
    throw new Error("group key cannot be empty");
  }
  res.group = opts.group.trim();
}