refactor: group ui/ statusbar and window subdirs

Continue tidying the flat ui/ root:

- ui/statusbar/: statusbar.rs becomes statusbar/mod.rs (its
  crate::ui::statusbar::* paths are preserved) and absorbs
  statusbar_config.rs + statusbar_menu.rs.
- ui/window/: the standalone manager/dialog windows move here —
  about, layout_manager, page_setup, plugin_manager, shortcuts,
  layers, update_notice, open_progress. The crate::ui::LayerPanel
  re-export is repointed so callers are unchanged.

Call sites repointed to the new paths; no compat re-exports beyond the
existing LayerPanel one. ui/ root drops from 21 to 10 flat files with
five subdirs (ribbon, style, popup, statusbar, window).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/ui/mod.rs

@@ -2,33 +2,24 @@
 /// Change this to scale the ribbon, layer manager rows, and property panel rows uniformly.
 pub const ROW_H: f32 = 26.0;
 
-pub mod about;
 pub mod app_menu;
 pub mod color_select;
 pub mod command_line;
 pub mod icons;
-pub mod layers;
-pub mod layout_manager;
 pub mod modal;
-pub mod open_progress;
 pub mod overlay;
-pub mod page_setup;
-pub mod plugin_manager;
 pub mod popup;
 pub mod properties;
 pub mod ribbon;
 pub mod side_toolbar;
-pub mod shortcuts;
 pub mod statusbar;
-pub mod statusbar_config;
-pub mod statusbar_menu;
 pub mod style;
 pub mod text_util;
-pub mod update_notice;
+pub mod window;
 
 pub use app_menu::AppMenu;
 pub use command_line::CommandLine;
-pub use layers::LayerPanel;
 pub use properties::PropertiesPanel;
 pub use ribbon::Ribbon;
 pub use statusbar::StatusBar;
+pub use window::layers::LayerPanel;

src/ui/statusbar/mod.rs

@@ -1,5 +1,8 @@
 //! Bottom status bar — Model/Layout tabs + OSNAP toggle + status info
 
+pub mod statusbar_config;
+pub mod statusbar_menu;
+
 use iced::widget::tooltip::Position as TipPos;
 use iced::widget::{button, column, container, mouse_area, row, text, text_input, tooltip, Row};
 use iced::{Background, Border, Color, Element, Length, Theme};
@@ -10,7 +13,7 @@ pub const LAYOUT_RENAME_INPUT_ID: &str = "layout_rename_input";
 
 use crate::app::Message;
 use crate::snap::Snapper;
-use crate::ui::statusbar_config::{StatusBarConfig, StatusPill};
+use crate::ui::statusbar::statusbar_config::{StatusBarConfig, StatusPill};
 
 #[derive(Clone, Default)]
 pub struct StatusBar {

src/ui/statusbar/statusbar_menu.rs

@@ -6,7 +6,7 @@ use iced::widget::{button, column, container, mouse_area, row, text};
 use iced::{Background, Border, Color, Element, Fill, Length, Padding, Theme};
 
 use crate::app::Message;
-use crate::ui::statusbar_config::{StatusBarConfig, StatusPill};
+use crate::ui::statusbar::statusbar_config::{StatusBarConfig, StatusPill};
 
 /// Full-screen overlay: transparent click-catcher + the menu panel pinned to
 /// the bottom-right, just above the status bar.

src/ui/window/mod.rs

@@ -0,0 +1,8 @@
+pub mod about;
+pub mod layout_manager;
+pub mod page_setup;
+pub mod plugin_manager;
+pub mod shortcuts;
+pub mod layers;
+pub mod update_notice;
+pub mod open_progress;