- Switch interaction from keyboard to a collapsible egui 'Controls' panel with grouped sections (Camera/Disk/Doppler/Renderer/Background/Grid/Planets) - Pin bevy_egui 0.41.0 (verified against crates.io: bevy ^0.19 + egui ^0.35) - Add Dependencies section §0; add src/ui.rs to file structure - Clarify mouse-input routing between egui panel and orbit controller