refactor(extension): reuse async detach() in registerListeners

[jackwener]

Follow-up to #322.

Replace the inline sync chrome.debugger.detach() in registerListeners onUpdated callback with the shared async detach() function.

Before

chrome.tabs.onUpdated.addListener((tabId, info) => {
  if (info.url && !isDebuggableUrl(info.url)) {
    if (attached.has(tabId)) {
      attached.delete(tabId);
      try { chrome.debugger.detach({ tabId }); } catch { /* ignore */ }
    }
  }
});

After

chrome.tabs.onUpdated.addListener(async (tabId, info) => {
  if (info.url && !isDebuggableUrl(info.url)) {
    await detach(tabId);
  }
});

This ensures consistent cleanup behavior across all detach paths and properly awaits the debugger detach. Extension build verified ✅ (16.62 kB).