Stale project state from prior live_gui tests (shared session-scoped
subprocess) was leaking into subsequent tests, causing the
test_full_live_workflow race condition: 'Project not switched' errors
when self.project still claimed to be a different project.
The fix: _handle_reset_session now mirrors the default-project branch
of __init__ (lines 1743-1745), creating a fresh default project dict,
clearing active_project_path and project_paths, and reinitializing
the workspace manager.
- src/app_controller.py: 6 new lines in _handle_reset_session
- tests/test_handle_reset_session_clears_project.py: 3 tests
(active_project_path, project_paths, self.project)
