Add keyboard navigation support for deleting selected LoRA entries using Backspace key while preventing accidental deletion when editing strength input values. The implementation includes:
- Backspace key now deletes selected LoRA when pressed outside strength inputs
- Backspace is ignored when focused on strength input fields to allow normal text editing
- Added corresponding test cases to verify both deletion and non-deletion scenarios
This prevents users from accidentally deleting LoRA entries while editing strength values and provides intuitive keyboard controls for LoRA management.