[ML 0.5/MVI.02] - Basic Interactions & Use Case Extraction

🎯 The objective

Migrate core message list interactions (selection, read/unread, star, delete, spam) from the MessagingController and Fragment to the new ViewModel and dedicated Use Cases.

🦮 Rules of the Road

🟢 In Scope

• Extract "Toggle selection" to ViewModel state change (Just state change, need the message list items to be using the new state)
• Extract "Select all" to ViewModel state change (same as above)
• Extract "Mark as read/unread" to ChangeMessageReadStatusUseCase (Partially covered by #10510)
• Extract "Add/remove star" to AddRemoveStartUseCase (Partially covered by #10510)
• Extract "Delete" action to DeleteMessageUseCase (#10517, #10518)
• Extract "Spam" action to MarkUnmarkMessageAsSpamUseCase (Covered by #10509)

🔴 Out of Scope

• Complex navigation flows (Move/Archive dialogs)

🚧 Technical and/or Business Requirements

• Selection Logic: "Toggle selection" and "Select all" should be pure state changes in the VM; the UI must reflect this state without Fragment-side logic.
• Use Case Extraction:
  • Logic currently inside MessagingController (Read, Star, Delete, Spam) must be extracted to Use Cases.
  • The VM should call these Use Cases directly.