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>

presentation/shell/session_events.py

@@ -106,4 +106,4 @@ class SessionEventsMixin:
         """Project được tạo/sửa/xoá: gom nhóm lại cột lịch sử và cập nhật nhãn thư mục."""
         self.sidebar.refresh()                 # History regroups by project
         self.cowork._apply_output_folder_label()  # project may have been renamed
-        self.structure._refresh_project_combo()   # GraphRAG's project lock list follows too
+        self.structure.refresh_project_list()      # GraphRAG's project lock list follows too