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/entities/common.rs

@@ -951,25 +951,34 @@ pub(crate) fn tapered_band_points(
     let seg_count = if is_closed { n } else { n.saturating_sub(1) };
     let mut pts: Vec<[f64; 3]> = Vec::with_capacity(seg_count + 1);
     let mut widths: Vec<f32> = Vec::with_capacity(seg_count + 1);
-    let mut push = |x: f64, y: f64, w: f32| {
-        let (wx, wy, wz) = to_wcs(x, y);
-        pts.push([wx, wy, wz]);
+    let mut push = |xy: Option<(f64, f64)>, w: f32| {
+        // `None` is the NaN separator that breaks the band.
+        pts.push(xy.map_or([f64::NAN; 3], |(x, y)| to_wcs(x, y).into()));
         widths.push(w);
     };
+    let mut prev_end_width: Option<f64> = None;
     for i in 0..seg_count {
         let (p0, bulge, sw0, ew0) = verts[i];
         let (p1, _, _, _) = verts[(i + 1) % n];
-        if i == 0 {
-            push(p0[0], p0[1], sw0 as f32);
+        match prev_end_width {
+            None => push(Some((p0[0], p0[1])), sw0 as f32),
+            // A segment starting at another width than the last one ended
+            // steps there: break the band and restart it (#1628).
+            Some(prev) if (prev - sw0).abs() > 1e-9 => {
+                push(None, 0.0);
+                push(Some((p0[0], p0[1])), sw0 as f32);
+            }
+            Some(_) => {}
         }
+        prev_end_width = Some(ew0);
         if bulge.abs() < 1e-9 {
-            push(p1[0], p1[1], ew0 as f32);
+            push(Some((p1[0], p1[1])), ew0 as f32);
         } else if let Some(arc) = BulgeArc::from_bulge(p0, p1, bulge) {
             let samples = arc.tessellate_angle(kernel::tessellation::DEFAULT_ANGLE);
             let segments = samples.len().saturating_sub(1).max(1);
             for (index, s) in samples.into_iter().enumerate().skip(1) {
                 let t = index as f64 / segments as f64;
-                push(s[0], s[1], (sw0 + (ew0 - sw0) * t) as f32);
+                push(Some((s[0], s[1])), (sw0 + (ew0 - sw0) * t) as f32);
             }
         }
     }