fix(email): retire legacy SMTP follow-up

Keep follow-up draft generation but remove the direct application SMTP delivery boundary. Route users to the provider-aware Job email flow and return 410 for legacy API callers.

job-tracker-ui/src/end-to-end-trust-loop.test.tsx

@@ -217,7 +217,7 @@ describe('end-to-end trust loop', () => {
     expect(await screen.findByText(/follow-up context/i)).toBeInTheDocument();
     expect(await screen.findByText(/saved application package material is available for reuse/i)).toBeInTheDocument();
     expect(await screen.findByText(/manual send boundary/i)).toBeInTheDocument();
-    expect(await screen.findByText(/the only outbound step is the explicit “send and log email” action below/i)).toBeInTheDocument();
+    expect(await screen.findByText(/open job email.*connected provider.*final confirmation/i)).toBeInTheDocument();
 
     fireEvent.click(screen.getByRole('tab', { name: /tailored cv/i }));
 
@@ -243,6 +243,7 @@ describe('end-to-end trust loop', () => {
     fireEvent.click(screen.getByRole('tab', { name: /follow up/i }));
 
     expect(await screen.findByDisplayValue(/i wanted to follow up on the backend developer thread/i)).toBeInTheDocument();
+    expect(screen.getByRole('link', { name: /open job email/i })).toHaveAttribute('href', '/correspondence');
     expect(mockedApi.post.mock.calls.some(([url]) => url === '/jobapplications/42/send-followup')).toBe(false);
   });
 });