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 <[email protected]>

src/io/font_repo.rs

@@ -82,7 +82,10 @@ pub fn missing_shx_fonts(doc: &CadDocument) -> Vec<String> {
         // The primary font and the big font (Asian double-byte glyphs) are
         // both plain .shx files the style depends on.
         for file in [style.font_file.trim(), style.big_font_file.trim()] {
-            if file.is_empty() || !file.to_ascii_lowercase().ends_with(".shx") {
+            if file.is_empty()
+                || !file.to_ascii_lowercase().ends_with(".shx")
+                || crate::io::linetypes::is_bundled_shape_file(file)
+            {
                 continue;
             }
             let resolved = crate::io::resolve_image_file(file, base).is_some()

src/io/linetypes.rs

@@ -345,6 +345,13 @@ fn bundled_shape_name(file: &str, number: i16) -> Option<&'static str> {
         .map(|(_, name, _)| *name)
 }
 
+/// Whether `file` is a shape file the bundled LFF substitutes stand in for,
+/// so its absence on disk never needs reporting.
+pub fn is_bundled_shape_file(file: &str) -> bool {
+    let stem = shape_file_stem(file);
+    BUNDLED_SHAPES.iter().any(|(f, _, _)| *f == stem)
+}
+
 /// The drawing's shape-file STYLE for `file`, added when missing (an empty
 /// name, as shape files are stored).
 fn shape_file_style(doc: &mut CadDocument, file: &str) -> codec::Handle {

src/io/mod.rs

@@ -170,9 +170,10 @@ impl From<&str> for OpenLoadError {
 pub async fn pick_open_path() -> Option<(PathBuf, u64)> {
     let handle = crate::sys::file_dialog()
         .set_title(crate::t!("Open CAD file").as_ref())
-        .add_filter(crate::t!("CAD Files").as_ref(), &["dwg", "dxf", "bak", "sv$", "DWG", "DXF", "BAK"])
+        .add_filter(crate::t!("CAD Files").as_ref(), &["dwg", "dxf", "dwt", "bak", "sv$", "DWG", "DXF", "DWT", "BAK"])
         .add_filter(crate::t!("DWG Files").as_ref(), &["dwg", "DWG"])
         .add_filter(crate::t!("DXF Files").as_ref(), &["dxf", "DXF"])
+        .add_filter(crate::t!("Drawing Template (*.dwt)").as_ref(), &["dwt", "DWT"])
         .add_filter(crate::t!("Backup / Autosave").as_ref(), &["bak", "sv$", "BAK"])
         .add_filter(crate::t!("All Files").as_ref(), &["*"])
         .pick_file()
@@ -1761,6 +1762,16 @@ mod save_failure_tests {
 /// picked from outside the plot styles folder is copied into it (unless a
 /// file of that name is already there), so the dialog lists it from now on
 /// and page setups naming it resolve after a restart.
+/// Pick a `.lin` linetype definition file and return its text (#1588).
+pub async fn pick_linetype_file() -> Option<String> {
+    let handle = crate::sys::file_dialog()
+        .set_title(crate::t!("Load Linetypes").as_ref())
+        .add_filter(crate::t!("Linetype Files").as_ref(), &["lin", "LIN"])
+        .pick_file()
+        .await?;
+    Some(String::from_utf8_lossy(&handle.read().await).into_owned())
+}
+
 pub async fn pick_plot_style() -> Result<Option<plot_style::PlotStyleTable>, String> {
     let dialog = crate::sys::file_dialog()
         .set_title(crate::t!("Load Plot Style Table").as_ref())

src/io/pdf_export.rs

@@ -771,7 +771,9 @@ fn append_pdf_page(
         }
         // Near-white and near-yellow (viewport active border) → dark grey for print
         // (only when no CTB override was applied).
-        if !color_overridden {
+        // `aci == 0` is an explicit true colour and plots as drawn, like the
+        // hatch pass (#1621); only a pure white there is an unresolved colour 7.
+        if !color_overridden && (wire.aci != 0 || [r, g, b] == [1.0; 3]) {
             // An authored white (not colour 7) plots as drawn, like on screen.
             let is_light = r > 0.80
                 && g > 0.80