//! The left-control-panel modules — one file per panel, each following ONE
//! pattern so parallel agents can add a new panel with minimal conflict:
//!
//! * a small state struct (its own editing buffers only);
//! * a `show(&mut self, ui: &mut egui::Ui, state: &mut EngineState, …)` method
//! the shell calls — `EngineState` (brep-render) stays the single brain,
//! borrowed in; pass the `Store` where a panel persists.
//!
//! Adding a panel = add `panels/<name>.rs` (state struct + `show`), `pub mod
//! <name>;` here, one field on `BrepApp`, and one `self.<name>.show(…)` call in
//! the shell. See `brep-app/README.md` → "Adding a panel".