Sheet sets: Place on Sheet, sheet view menus, block lists, missing status, field refresh

Model Views lists named model views and places them on the current sheet
(xref, viewport, paper-space named view, view label with navigation
fields, sheet view record); sheet view rows get Display, Rename & Renumber
View, Set category, Place Callout Block and Place View Label Block; the
View Category dialog's Add Blocks opens List of Blocks / Select Block; a
sheet whose relative path is gone shows missing; sheet set fields store
their values when a set changes; named views keep their centre relative to
the target. Codec pin moves to the revision with these field helpers.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/app/update/file.rs

@@ -5520,12 +5520,9 @@ impl OpenCADStudio {
         let half_w = view.width.abs() * 0.5;
         let half_h = view.height.abs() * 0.5;
         (half_w > 1e-9 && half_h > 1e-9).then_some(())?;
-        self.area_plot_job((
-            view.center.x - half_w,
-            view.center.y - half_h,
-            view.center.x + half_w,
-            view.center.y + half_h,
-        ))
+        // The view centre is relative to its target (plan views).
+        let (cx, cy) = (view.target.x + view.center.x, view.target.y + view.center.y);
+        self.area_plot_job((cx - half_w, cy - half_h, cx + half_w, cy + half_h))
     }
 
     pub(in crate::app) fn extents_plot_job(&self) -> Option<PdfPageInput> {