Backstage versus backdrop scoring error check

We had an issue at an event where a scoring referee scored in error nine Pixels in the backstage instead of on the backdrop. Fortunately, this was error was easy to identify when challenged by the team as the score also also showed 1 set-line bonus had be acheived. A set-line bonus is only possible when 3 or more pixels are scored in the backdrop. We therefore concluded that all 9 pixels scored in the backstage were indeed scored on the backdrop becuase otherwise a set-line could not have been scored.

**Describe the solution you'd like**
I would like an error check in FTC live scoring that does not allow a set-line to be scored unless there are at least 3 Pixels on the backdrop. This will at least provide some warning that an referee may have incorrectly scored pixels on the backstage instead of the backdrop

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
see attached

No files, tests, or entry points are named. Start by locating the FTC live-scoring flow for set-line bonuses and backdrop pixel counts, then reproduce the described scoring sequence; the work is done when scoring a set-line with fewer than three backdrop pixels produces the requested warning or prevention.

Written by the indexing model from the issue text.