1.4.1 - held link survives a timed-out check

Fixed

• A held link no longer dies permanently after a timed-out check. A guardian check or command that hit its deadline reset the connection, which also cancelled the reconnect supervisor and left no client. In hold mode nothing reconnected afterwards until a user command ran - even while the fixture kept advertising. Observed live: disconnected for hours with no reconnect attempt logged.
• In hold mode an advertisement now re-arms the hold exactly once (never while a reset is still tearing down). Idle installs are unchanged.

832 tests pass; the new regression test fails on 1.4.0.