741558a6d4
- Removed the built-in `background` (`bg`) slash command and its `handleBackgroundCommand` path from the interactive flow. - Deleted background event subscription and shutdown handling by removing `handleBackgroundEvent` from the event, input, and interactive controllers. - Simplified `InteractiveModeContext` by dropping background-only fields and helpers such as `isBackgrounded`, background UI context creation, and background event callbacks.