cmux sidebar builder Use this skill when the task is to create or modify a cmux custom sidebar view. These are user/agent-authored files in rendered by cmux's runtime SwiftUI-style interpreter, not compiled app code. The primary dogfood surface is a normal Bonsplit pane tab opened with ; the left sidebar picker remains useful for previews. Orientation - The original work is PR by Aziz Albahar. - The feature is opt-in behind the UserDefaults-backed key . - Custom sidebars live under . They can be opened as normal Bonsplit pane tabs with and appear in the left sidebar picker when the beta is en…