Tasking: offer "open in a new window" when there's no Beacon Remote tab

[OSPFNeighbour]

What

When Tasking tries to open a URL in the Beacon Remote tab (openURLInBeacon) and there's no tab to reuse — none registered, or it was closed — the warning alert now:

• Explains the specific cause (no remote tab / tab closed / sent from the remote tab itself / unknown) and what to do about it, instead of echoing the raw background-script string.
• Includes an "Open this page in a new window" link to the target URL (target="_blank" rel="noopener noreferrer").
• Is centre-aligned and persists until dismissed, then auto-dismisses once the link is clicked.

Also guards against an undefined sendMessage response (previously threw on response.message).

Changes

• chromeRunTime.js — reason mapping + link + click-to-dismiss.
• windowAlert.js — showAlert returns the alert id; new closeAlert(id) helper (the timeout path reuses it).

Testing

• npx eslint clean on both files.
• Manual: not yet exercised in the extension — needs a check that the alert renders and the link opens/dismisses.

🤖 Generated with Claude Code