refactor(gui): move the shared binding-editor chrome out of features/mouse

features/mouse/picker.rs is, by its own first line, "shared action-catalog rows and menu surfaces used by binding editors", and five of its seven importers are not the mouse: the keyboard function row and its editors, the profile picker and shell, and the Actions Ring editor all reach into features::mouse for it.

Pure move to features/binding_editor.rs, file unchanged. features::mouse keeps the old path alive as an alias for this one commit so that nothing else has to change with the move; the next commit updates the imports and drops it.