fix(dashboard): transaction links were 13px tall

Found only when the harness ran against the deployed site. Locally the check
waited a flat 600ms for the invoice table and the fast dev server had not filled
it yet, so it measured an empty table and saw no links at all. The remote host
was slow enough that the rows were there.

The harness now waits for a row rather than a stopwatch, which is the reason it
could pass while the defect was in front of it, and the same mutation that
produced this finding now turns it red.