feat(python): linetypes and layouts (doc.linetypes, doc.layouts)

TableOperation gains simple-linetype create/modify/rename/delete (standard names
taken, rename follows layers and entities, guarded delete) and paper-space
layout create/rename/delete/set-current/set-page (default page setup and sheet
viewport, the application's own layout switch, Model protected). CTAB now reports
the current layout. Real-IPC audit with DWG/DXF persistence and undo, IPC and
Python unit tests, docs.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

crates/ocs_plugin_api/src/ipc/v4/protocol.rs

@@ -145,6 +145,15 @@ mod tests {
                 block: "C".into(),
                 entity: acadrust::EntityType::Line(acadrust::entities::Line::new()),
             },
+            TableOperation::LinetypeCreate { name: "L".into(), description: "d".into(), pattern: vec![1.0, -1.0] },
+            TableOperation::LinetypeModify { name: "L".into(), description: None, pattern: Some(vec![2.0, -2.0]) },
+            TableOperation::LinetypeRename { from: "L".into(), to: "M".into() },
+            TableOperation::LinetypeDelete { name: "M".into() },
+            TableOperation::LayoutCreate { name: "S".into() },
+            TableOperation::LayoutRename { from: "S".into(), to: "T".into() },
+            TableOperation::LayoutDelete { name: "T".into() },
+            TableOperation::LayoutSetCurrent { name: "Model".into() },
+            TableOperation::LayoutSetPage { name: "S".into(), paper_size: Some([420.0, 297.0]), rotation: Some(90), scale: Some([1.0, 50.0]) },
         ] {
             let bytes = bincode::serialize(&PluginRequest::TableOperation { operation: operation.clone() }).unwrap();
             assert!(matches!(bincode::deserialize::<PluginRequest>(&bytes).unwrap(),