ocs_doc_api: fix stray impl-closing brace in both mock backends

The loft/attributes/viewport mock methods were appended after the impl block's
closing brace, orphaning add_vertex..finalize_op and leaving a duplicate brace.
Move the impl close to the true end in both tests/mock_backend.rs and
examples/common/mod.rs. Crate tests (8) + examples compile green again.

crates/ocs_doc_api/examples/common/mod.rs

@@ -225,7 +225,6 @@ impl DocApiBackend for MockBackend {
     fn viewport_view(&self, id: ObjectId) -> ApiResult<([f64; 3], f64)> {
         self.viewport_views.get(&id).copied().ok_or(ApiError::UnknownId(id))
     }
-}
     fn add_vertex(&mut self, id: ObjectId, _at: usize, _point: [f64; 3]) -> ApiResult<()> {
         if self.entity_exists(id) {
             Ok(())

crates/ocs_doc_api/tests/mock_backend.rs

@@ -166,7 +166,6 @@ impl DocApiBackend for MockBackend {
     fn viewport_view(&self, id: ObjectId) -> ApiResult<([f64; 3], f64)> {
         self.viewport_views.get(&id).copied().ok_or(ApiError::UnknownId(id))
     }
-}
     fn add_vertex(&mut self, id: ObjectId, _at: usize, _point: [f64; 3]) -> ApiResult<()> {
         if self.entity_exists(id) {
             Ok(())