Fixes a scheduler-dependent flake in chatd's dial-timeout recovery path.
The dial timeout now uses the server's quartz clock, and
`dialWithLazyValidation` also uses that clock for its validation-delay
timer. If a dial result races with a canceled parent context, the
cancellation now wins instead of treating the cancellation-produced dial
error as a fast failure that triggers eager validation.
The recovery-threshold test now traps and advances the mock clock, which
keeps strict DB expectations without depending on wall time or goroutine
scheduling.
Closes https://github.com/coder/internal/issues/1569
Closes ENG-2838
Ethan
f3c25de7aa