Add type hints to GraphModel properties and fix documentation

src/power_grid_model_ds/_core/model/graphs/models/base.py

@@ -29,12 +29,12 @@ def __init__(self, active_only=False) -> None:
 
     @property
     @abstractmethod
-    def nr_nodes(self):
+    def nr_nodes(self) -> int:
         """Returns the number of nodes in the graph"""
 
     @property
     @abstractmethod
-    def nr_branches(self):
+    def nr_branches(self) -> int:
         """Returns the number of branches in the graph"""
 
     @property
@@ -251,7 +251,7 @@ def get_all_paths(self, ext_start_node_id: int, ext_end_node_id: int) -> list[li
         return [self._internals_to_externals(path) for path in internal_paths]
 
     def get_components(self) -> list[list[int]]:
-        """Returns all separate components when the substation_nodes are removed of the graph as lists
+        """Returns all separate components of the graph as lists
 
         If you want to get the components of the graph without certain nodes,
         use the `tmp_remove_nodes` context manager.

src/power_grid_model_ds/_core/model/graphs/models/rustworkx.py

@@ -26,11 +26,11 @@ def __init__(self, active_only=False) -> None:
         self._external_to_internal: dict[int, int] = {}
 
     @property
-    def nr_nodes(self):
+    def nr_nodes(self) -> int:
         return self._graph.num_nodes()
 
     @property
-    def nr_branches(self):
+    def nr_branches(self) -> int:
         return self._graph.num_edges()
 
     @property