fix(graphrag): crash on project rename/path change (DF-009)

session_events.py::_on_projects_changed (runs on every project
create/rename/delete) called self.structure._refresh_project_combo() —
but that method only ever existed on GraphRenderer, not on
StructureGraphView itself (self.structure). Renaming a project or
changing its working-directory path raised AttributeError and crashed
the app.

Add StructureGraphView.refresh_project_list(), matching the existing
schedule_rescan/set_project/prewarm forwarding pattern, and call that
instead. Add a regression test
(test_refresh_project_list_forwards_to_renderer).

Logged as DF-009 in Task Tracking Template.xlsx — root cause, fix and
regression test recorded (row was empty in this local copy despite
being reported as already logged there).

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

tests/integration/test_structure_graph_view.py

@@ -55,6 +55,25 @@ def test_structure_graph_view_builds(ctx):
     assert view.qa is not None
 
 
+def test_refresh_project_list_forwards_to_renderer(ctx):
+    """Crash bug: ``presentation/shell/session_events.py::_on_projects_changed``
+    called ``self.structure._refresh_project_combo()`` — a method that only
+    ever existed on ``GraphRenderer``, not on ``StructureGraphView`` itself —
+    so creating/renaming/deleting a project (anywhere in the app) raised
+    ``AttributeError`` and crashed. ``refresh_project_list()`` is the public
+    forwarding method callers must use instead (matching ``schedule_rescan``/
+    ``set_project``/``prewarm``'s existing forwarding pattern)."""
+    from cowork_local.presentation.graph.structure_graph_view import StructureGraphView
+
+    view = StructureGraphView(ctx)
+    assert not hasattr(view, "_refresh_project_combo")
+
+    combo = view.renderer.project_combo
+    before = combo.count()
+    view.refresh_project_list()   # must not raise
+    assert combo.count() == before   # re-populated from the same project list, same size
+
+
 def test_render_populates_the_scene_and_emits_graph_rendered(ctx, tmp_path):
     from cowork_local.presentation.graph.graph_renderer import GraphRenderer