Update signal and power capacity to be pixel-load based

- Change signal capacity calculation to be pixel-load based (DVI default: 491,520 pixels per run)
- Change power capacity calculation to use pixel-derived watt load (DVI budget: 262,144 pixels)
- Refactor limits and groups calculation logic to dynamically evaluate limits using pixel dimensions and cabinet reference wattage
- Update status display, helper texts, and CSV exports to report limits in pixel/load budgets
- Adjust test case presets to match the new pixel-based capacity constraints

Author: Dvi256