[ML 0.1/UI.04.10] - Verify selection mode and favourite toggle with legacy action mode

[rafaeltonholo]

Blocked by

• [ML 0.1/UI.04.2] - Implement legacy message list loading bridge #10775

Description

The state machine handles ToggleSelectMessages and ToggleFavourite events with state transitions, but end-to-end verification is needed to confirm these correctly propagate to the legacy MessageListFragment action mode (contextual action bar, batch operations, star toggle persistence).

Acceptance Criteria

• Long-pressing a message enters selection mode and activates the legacy contextual action bar.
• Selecting/deselecting messages updates the legacy selection state.
• Toggling favourite/star persists through the legacy flag mechanism.
• Exiting selection mode (back press, deselect all) correctly clears legacy state.
• Behaviour matches the legacy XML-based message list.

Out of Scope:

• Modifying the contextual action bar UI.
• Changing selection or favourite business logic.