Cargo: codec aad7053, kernel 1a52eaf, graph 263de59; honour viewport clipping

Brings codec PRs #84 (cross-version visual styles, table styles,
subentity managers), #88 (viewport clipping flag, DXF boundary handle),
#89 (DXF viewport snap/twist in degrees) and #92 (field format codes,
event updates).

With #88 a viewport keeps a stored boundary whether or not clipping is
on, so a linked boundary alone no longer means "clipped": rendering,
paper picking, VPCLIP and the Clipped property check the clipping flag
too, and VPCLIP / MVIEW Object and Polygon set it. Before, OCS never set
the flag, so its clipped viewports opened rectangular elsewhere.

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

src/modules/insert/xclip.rs

@@ -497,7 +497,7 @@ impl CadCommand for ClipCommand {
             }
             // The layout's own paper-space viewport (id 1) is not clippable.
             Some(EntityType::Viewport(vp)) if vp.id != 1 => {
-                let clipped = !vp.clip_boundary_handle.is_null();
+                let clipped = crate::entities::viewport::is_clipped(&vp);
                 self.inner = Some(Box::new(MviewCommand::vpclip(handle, clipped)));
                 CmdResult::NeedPoint
             }

src/modules/layout/mview.rs

@@ -799,7 +799,7 @@ impl CadCommand for MviewCommand {
         if self.step == Step::ClipSelect {
             return match self.picked.take() {
                 Some(EntityType::Viewport(vp)) if vp.id != 1 => {
-                    self.clip = Some((handle, !vp.clip_boundary_handle.is_null()));
+                    self.clip = Some((handle, crate::entities::viewport::is_clipped(&vp)));
                     self.step = Step::ClipChoice;
                     CmdResult::NeedPoint
                 }