fix: open-issue sweep — drawing, plot, snap, layout and UI fixes

Fixes:
- Font prompt no longer lists bundled ltypeshp/qcadshp shape files (#1626)
- Wide polylines step at a discontinuous segment width; PEDIT marks the
  current vertex; keyword steps refresh the command preview (#1628)
- Radius-0 fillet drops the zero-length segment it left, so the corner
  fillets again (#1422)
- FILLET Trim / No trim option (#1558)
- True-colour wires plot in their own colour; colour picker stores the
  value it shows (#1621)
- Model tab keeps its page setup; "Save changes to layout" in Model (#1620)
- QNEW default template in Options > Files; .dwt in the open dialog
  (#1134, #1113)
- GRIDUNIT / GRIDMODE / PERSPECTIVE variables (#1618, #1524)
- PTYPE (#1433)
- ZOOM nX / nXP (#1465)
- CHSPACE between model and paper space through a viewport (#1428)
- Moving a dimension keeps its automatic text placement
- Shell icon; "&&" button labels (#1554)
- LINETYPE Load from a .lin file (#1588)
- XLINE / RAY hide the crosshair arms (#1437)
- Dynamic-input boxes keep clear of the crosshair and each other (#1546)
- Snap marker colour setting, dark default on light canvases
  (#1497, #1229, #1128)
- Dimension style precision as a 0.00 pattern dropdown (#1426)
- Node graph nodes left of the origin no longer clip away (#1592)
- Collapse button in the command history header (#1094)
- Freeze-in-current-viewport toggle in the ribbon layer list (#1466)
- Geometric Center object snap for closed polylines (#1369)

New strings translated in all 21 locales.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/layers.rs

@@ -88,6 +88,11 @@ impl OpenCADStudio {
             return;
         }
         let active = self.tabs[i].active_layer.clone();
+        let vp_column = self.tabs[i].scene.active_viewport.and_then(|vp| {
+            (self.tabs[i].scene.current_layout != "Model")
+                .then(|| self.tabs[i].layers.vp_cols.iter().position(|c| c.handle == vp))
+                .flatten()
+        });
         let infos: Vec<crate::ui::ribbon::LayerInfo> = self.tabs[i]
             .layers
             .layers
@@ -100,6 +105,8 @@ impl OpenCADStudio {
                 visible: l.visible,
                 frozen: l.frozen,
                 locked: l.locked,
+                vp_frozen: vp_column
+                    .map(|column| (column, l.vp_frozen.get(column).copied().unwrap_or(false))),
             })
             .collect();
         let names: Vec<String> = infos.iter().map(|l| l.name.clone()).collect();