fix: show oauth url and code properly on device auth popup

- Auth flow now waits for user's Enter before starting
- Start auth only when user presses Enter on DeviceAuth popup
- Proper error handling: missing GOOGLE_CLIENT_ID shows clear message
- Error messages displayed in popup with Retry option
- Popup shows instructions before auth, URL+code during auth
- Handle both verification_url and verification_uri field names from Google
- Check HTTP status code and show error_description on failures
- AuthError propagated to render function for display
- Popup border turns green when URL+code are ready

src/main.rs

@@ -88,6 +88,7 @@ fn main() -> io::Result<()> {
                 network_status: &app.network_status,
                 task_list_scroll: app.task_list_scroll,
                 detail_scroll: app.detail_scroll,
+                auth_error: app.auth_error.as_deref(),
             };
             draw(frame, view);
         })?;