Preserve class-local member definition order

`handle_class()` now uses a new _iter_class_members() helper that:

- preserves class_.__dict__ definition order for class-local members
- then appends additional visible members from dir()/getattr() so
  inherited or lazily exposed names are still seen

That makes nested class discovery consistent with the earlier
module-level fix, so the printer's topological sort now gets real
definition order as its stable tie-break for nested classes too.

Author: ax3l

pybind11_stubgen/parser/mixins/parse.py

@@ -48,7 +48,7 @@ class ParserDispatchMixin(IParser):
     def handle_class(self, path: QualifiedName, class_: type) -> Class | None:
         base_classes = class_.__bases__
         result = Class(name=path[-1], bases=self.handle_bases(path, base_classes))
-        for name, member in inspect.getmembers(class_):
+        for name, member in self._iter_class_members(class_):
             obj = self.handle_class_member(
                 QualifiedName([*path, Identifier(name)]), class_, member
             )
@@ -70,6 +70,24 @@ def handle_class(self, path: QualifiedName, class_: type) -> Class | None:
                 raise AssertionError()
         return result
 
+    def _iter_class_members(self, class_: type):
+        seen: set[str] = set()
+
+        # Preserve definition order for class-local members, then append any
+        # inherited or lazily exposed members that are visible via dir/getattr.
+        for name, member in class_.__dict__.items():
+            seen.add(name)
+            yield name, member
+
+        for name in dir(class_):
+            if name in seen:
+                continue
+            try:
+                member = getattr(class_, name)
+            except AttributeError:
+                continue
+            yield name, member
+
     def handle_class_member(
         self, path: QualifiedName, class_: type, member: Any
     ) -> Docstring | Alias | Class | list[Method] | Field | Property | None: