[Feature]: Add visual element of floor beams resembling original game (graphics)

Problem / motivation

Nearly 1/4 of the vertical space is beams . The art on the beams in the lobby has little stains on the lobby beams and none on most of the units. Restoring the beams will give the floors more of a visual sense of rigidity and floor-based division. Right now it is a little too easy to get lost visually.

Proposed solution

Add more of the beams style back into the game.
Multi floor installations do not have beams. Beams are aligned with the top of the cell. The floor of a cell is just above its basement unit's beam. At the beginning the lobby would have no beam beneath it. beams also as neutral dark gray and static, help the other areas contrast and pop to life as well as show the elevator shafts cutting through them.

This would involve adding procedural art changes that would alter the look of pretty much every existing building unit in the game significantly.

Alternatives considered

n/a

Which game mode should this target?

Both / mode-agnostic

Before submitting

• I searched existing issues and this is not a duplicate.

example screenshot via. https://superfuntimevideogaminggirl.com/2016/10/03/oldies-but-goodies-sim-tower/

No files or tests are identified. Start by locating the procedural art code for building units, then review how cell tops, basement beams, multi-floor installations, the lobby, and elevator shafts are represented; done means beams render consistently in both modes with the described alignment and neutral static styling.