fix(tolerance): complete workflow integration

Sync current main and companion codec changes before preserving unsupported frame rows, rendering in the entity plane, and sharing final layout metrics with placement preview.

src/scene/convert/tess.rs

@@ -528,7 +528,7 @@ fn tessellate_entity_inner(
     if let EntityType::Viewport(vp) = e {
         // The sheet viewport (overall/id=1) is never shown — it represents the
         // paper boundary, not a user-defined content window.
-        if !Scene::is_content_viewport(vp) {
+        if Scene::is_sheet_viewport(document, vp) {
             return vec![];
         }
         let is_active = active_viewport == Some(h);