8ea5237991
## Summary
- The "Load remote images" snack bar in single-mail view (and the analogous thread view) never disappeared on its own — the user had to interact with it.
- Flutter's `SnackBar` defaults to `persist: true` whenever an `action` is provided (see `flutter/lib/src/material/snack_bar.dart`: `persist = persist ?? action != null`), which short-circuits the duration-based dismiss timer in `ScaffoldMessengerState.build`:
```dart
_snackBarTimer = Timer(snackBar.duration, () {
if (snackBar.persist) return; // <-- here
hideCurrentSnackBar(reason: SnackBarClosedReason.timeout);
});
```
So the explicit `duration: 3s` was set, but the "View" action made the snack bar persistent and the timer's callback returned early.
- Pass `persist: false` explicitly on both snack bars so the 3-second timer fires and the snack bar slides away on its own, while the "View" action button still works to navigate to the trusted-senders settings.
## Test plan
- [x] Added widget regression test in `test/widget/email_detail_screen_test.dart` (`Load remote images snack bar auto-dismisses after 3 seconds`).
- [x] Added analogous test in `test/widget/thread_detail_screen_test.dart`.
- [x] `task test-widget` — all 174 widget tests pass.
- [x] `scripts/run_unit_tests.sh` — all 552 unit tests pass.
- [x] `fvm dart analyze --fatal-infos` on changed files — no issues.
- [x] `fvm dart format` — no diffs.
- [ ] Manual: open a single mail with HTML body from an untrusted sender; tap "Load remote images"; verify the snack bar appears, images load, and the snack bar disappears after ~3 seconds while the "View" action button still navigates to `/accounts/trusted-senders` when tapped.
Closes #484
Co-authored-by: Agentloop Bot <agentloop-bot@noreply.codeberg.org>
Reviewed-on: https://codeberg.org/guettli/sharedinbox/pulls/548