Remote Control renews this computer's credential before it expires

Remote Control lets you reach a Claude Code session on this computer from elsewhere. Before, it re-registered this computer only after the server rejected a connection, and stopped after a fixed number of tries. Now:

• It renews the computer's credential shortly before it expires, showing a message that it is doing so, and retries with randomized waits if renewal fails.
• Re-registering after a rejected connection is capped per hour and can report itself as paused.
• A new error message covers the server rejecting registration.
• When Remote Control gives up, the computer's registration can be kept on shutdown.