feat(FN-1899): add login timeout, cancellation, and 409 conflict handling

- Add LoginOutcome type ('pending' | 'success' | 'failed' | 'timeout') with state tracking
- Implement AbortController-based cancellation for OAuth login flows
- Add timeout detection after MAX_POLL_CYCLES (150 polls, ~5 min)
- Handle 409 Conflict when concurrent login is attempted
- Persist login outcomes to onboarding stepData for session recovery
- Add getStepData mock export to App.test.tsx vi.mock
- Fix ToastType: use 'info' instead of invalid 'warning' type

packages/dashboard/app/components/__tests__/ModelOnboardingModal.test.tsx

@@ -1321,7 +1321,7 @@ describe("ModelOnboardingModal", () => {
       await waitFor(() => {
         expect(addToast).toHaveBeenCalledWith(
           "Login already in progress. Please wait or cancel the current attempt.",
-          "warning"
+          "info"
         );
       });
     });
@@ -1517,7 +1517,7 @@ describe("ModelOnboardingModal", () => {
       });
 
       // Should show timeout toast
-      expect(addToast).toHaveBeenCalledWith("Login timed out. Please try again.", "warning");
+      expect(addToast).toHaveBeenCalledWith("Login timed out. Please try again.", "info");
 
       // Cancel button should not be shown after timeout
       expect(screen.queryByText("Cancel")).toBeNull();