feat: plot a model-space window to PDF

Pick a rectangular window in model space with the existing PLOTWINDOW command (now enabled in model space, previously paper-space only) and export it to a PDF at a chosen ISO paper size (A4-A0), orientation and scale (fit or ratio). The window is a hard clip boundary. Adds paper-size presets, a window-to-sheet transform, scale + clip support in the PDF exporter, and Page Setup controls (format/orientation/pick window).

src/modules/view/mod.rs

@@ -33,7 +33,7 @@ mod zoom_in;
 mod zoom_out;
 pub mod zoom_window;
 
-use crate::modules::{CadModule, RibbonGroup, RibbonItem};
+use crate::modules::{CadModule, IconKind, ModuleEvent, RibbonGroup, RibbonItem, ToolDef};
 
 pub struct ViewModule;
 
@@ -137,6 +137,19 @@ impl CadModule for ViewModule {
                         RibbonItem::Tool(cascade::tool()),
                     ],
                 },
+                // ── Plot ──────────────────────────────────────────────────────────
+                // Model space has no paper-space side toolbar, so Page Setup
+                // (format/orientation/pick window for PLOTWINDOW) needs an
+                // entry here too.
+                RibbonGroup {
+                    title: "Plot",
+                    tools: vec![RibbonItem::Tool(ToolDef {
+                        id: "PAGESETUP",
+                        label: "Page Setup",
+                        icon: IconKind::Svg(include_bytes!("../../../assets/icons/pagesetup.svg")),
+                        event: ModuleEvent::Command("PAGESETUP".to_string()),
+                    })],
+                },
             ]
         })
     }

src/modules/view/plot_window.rs

@@ -1,7 +1,7 @@
 // PLOTWINDOW command — pick two corners to define the plot window area.
 //
-// Works only in paper space layouts. After picking P1 and P2, writes the
-// window to the layout's PlotSettings (PlotType::Window).
+// In paper space it writes the layout's PlotSettings (PlotType::Window); in
+// model space the host stores the window for the plot dialog.
 
 use crate::command::{CadCommand, CmdResult};
 use crate::scene::model::wire_model::WireModel;