fix: Android app startup — INTERNET permission, MobSF scan, E2E robustness

- Add INTERNET permission to main AndroidManifest.xml (was missing from
  release builds, causing all network calls to fail on device)
- Add scripts/mobsf_scan.sh: uploads release APK to MobSF after each
  build and asserts required permissions are declared; docker pull -q
  suppresses progress-bar noise
- Wire MobSF scan into build-android task; add mobsf-stop convenience task
- Fix _AccountTile subtitle overflow on Android: replace Column([Text,Text])
  with single Text('email\ntype') so ListTile can measure height correctly
- E2E test robustness on Android: use pumpUntil(find.text('Alice')) instead
  of pumpUntil(FAB)+expect to handle Drift background-isolate stream delay;
  add skipOffstage:false to tap; remove stale email-address assertion
- Uninstall app before each Android integration test run to clear leftover
  DB state and prevent "Unable to start the app" on repeated runs
- Update widget tests to use find.textContaining for merged subtitle text

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

stalwart-dev/integration_android_test.sh

@@ -118,6 +118,10 @@ cd "$ROOT"
 "$ADB" -s "$EMULATOR_ID" reverse tcp:1430 tcp:"$STALWART_IMAP_PORT"
 "$ADB" -s "$EMULATOR_ID" reverse tcp:1025 tcp:"$STALWART_SMTP_PORT"
 
+# Clear any leftover app state from previous runs (stale DB, cached APK process).
+# This ensures "No accounts yet." on every fresh run and prevents install conflicts.
+"$ADB" -s "$EMULATOR_ID" uninstall com.example.sharedinbox 2>/dev/null || true
+
 ts "flutter test start"
 fvm flutter test integration_test/ -d "$EMULATOR_ID" | grep -Ev "was tree-shaken|Tree-shaking can be disabled"
 ts "flutter test done"