## Description Improve the reliability and clarity of the PC builder, particularly when handling saved data, missing prices, and compatibility messages. Currently, saved builds are loaded from localStorage without validation, missing component prices are treated as zero in the total, and empty builds display several unnecessary "Unknown" compatibility messages. ## Acceptance criteria - [ ] Validate saved build data before loading it from localStorage. - [ ] Handle invalid or corrupted saved data without crashing the application. - [ ] Clearly indicate when the total build price is incomplete due to missing component prices. - [ ] Display a simplified compatibility message when no components have been selected. - [ ] Ensure compatibility warnings and errors remain clearly visible when relevant. ## Dependencies None.