- Add explicit agent/model mode toggles to QuickChatFAB and NewChatDialog
- Update session target logic so model mode starts chats with the KB agent while agent mode uses selected agents
- Clear opposite selections when switching modes and adjust placeholders/disabled states to match active mode
- Expand ChatView and QuickChatFAB tests to cover toggle visibility, mode switching, and session payload behavior
- Add useQuickChat coverage to verify agent-only switchSession calls omit model parameters