t3_environment_link told the agent a machine was linked whenever a row
existed, and "Use this link" accepted it, even after the link expired.
The agent then failed on its first call and the user had no way to renew
it from the card. Both now treat an expired link as no link, so the card
asks for a new pairing code.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>