- Add `maintenance_mode: bool = False` flag to `SBABot.__init__`
- Register a global `@tree.interaction_check` that blocks non-admin users
from all commands when maintenance mode is active
- Update `admin_maintenance` command to set `self.bot.maintenance_mode`
and log the state change, replacing the no-op placeholder comment
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>