- Remove unconditional reset of ui_state.selected_craft_index in render_body_list_ui()
- Only reset ui_state.selected_craft_index to -1 when body is selected
- This prevents panel from disappearing in subsequent frames when spacecraft remains selected
- Remove selected_craft_index from RenderState, move to UIState
- Camera now always targets bodies (directly selected or parent of selected spacecraft)
- UI handles all spacecraft selection logic
- Remove ~30 lines of duplicate/special-case code from renderer
- Update all renderer functions to single body-focused path
- Update UI rendering functions to use ui_state->selected_craft_index
- Rename CelestialBody/Spacecraft position/velocity to global_*
- Add OrbitalElements struct to both bodies and spacecraft
- Rename old OrbitalElements to OrbitalMetrics (for output/analysis)
- Update all references throughout codebase
- Preserve parent_index in outer structs (not in OrbitalElements)
- Build succeeds with only unused variable warning
- Create ui_renderer.cpp/h with all raygui UI panel rendering functions
- Remove UI rendering code from renderer.cpp (421 lines moved)
- Remove UI state fields from RenderState, create separate UIState struct
- Remove raygui dependency from renderer module
- Update main.cpp to initialize UIState and call UI render functions
- Update documentation to reflect new module structure
- Improve separation of concerns between 3D rendering and UI overlays