LCFS - Exemption reporting and Non-assessment are mutually exclusive

**Describe the task**
Update the Compliance Report assessment options so that **Exemption reporting** and **Non-assessment** are mutually exclusive selections. Users must only be able to select one option at a time, preventing both options from being true simultaneously.

**Purpose**
These two selections represent different assessment outcomes and cannot logically occur together. Enforcing mutual exclusivity prevents inconsistent report states and ensures correct processing logic.

**Acceptance Criteria**
- [ ] The **Exemption reporting** and **Non-assessment** options cannot both be selected at the same time.
- [ ] Selecting **Exemption reporting** automatically unselects **Non-assessment** if it was previously selected.
- [ ] Selecting **Non-assessment** automatically unselects **Exemption reporting** if it was previously selected.
- [ ] The UI clearly reflects that only one of these options can be active at a time.
- [ ] Backend validation prevents both values from being stored as true simultaneously.

**Additional context**
- This logic applies to the Compliance Report assessment section used by IDIR analysts.
- Ensure existing reports with previously saved data are not broken by the validation change.