Complete Table host model coverage

Maps rows, columns, merged ranges, style and placement through the generic
generator (now with tuple and usize support), adds grid/merge/reference
validation, and keeps DXF cell merge dimensions in step with merged_ranges.
staged_python_table_lifecycle_over_real_ipc passes the full gate including
DWG and DXF reopen.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

plugins/opencad-python/src/ocs_module.rs

@@ -4756,7 +4756,7 @@ mod tests {
                 );
             }
         }
-        assert_eq!(emitted.len(), 26);
+        assert_eq!(emitted.len(), 27);
     }
 
     #[cfg(feature = "experimental-host-model")]