LCFS - Line 7 Maximum Retention Logic and Volume Re-entry Issues

**Describe the Bug**
Multiple issues with Line 7 retention logic and volume handling during supplemental reporting:

1. Maximum previously retained calculation is incorrectly based on current compliance year instead of previous year
2. Retained volume option not available when switching from below target to above target post-supplemental
3. Users must re-enter retained volumes during supplemental even when no changes occurred

**Expected Behaviour**
- Maximum previously retained should be based on the previous compliance year
- When switching from below target to above target after supplemental, retention options should become available
- Retained volumes should persist during supplemental unless explicitly changed
- Save functionality should allow completion without re-entering unchanged volumes

**Actual Behaviour**
- Maximum previously retained uses current compliance year data
- No retention options available after switching from below to above target
- All retained volumes must be manually re-entered during supplemental
- Users cannot complete supplemental without re-entering volumes even if unchanged

**Implications**
- Incorrect retention calculations affecting compliance
- Poor user experience requiring unnecessary data re-entry
- Risk of incomplete supplemental submissions
- Potential compliance calculation errors

**Steps To Reproduce**
User/Role: Supplier completing supplemental report
1. Navigate to compliance reporting
2. Complete initial report where organization is below target
3. Submit supplemental report that moves organization above target
4. Observe Line 7 retention options are not available
5. Attempt to complete supplemental without re-entering retained volumes
6. Observe system requires re-entry of all retained volumes

**Additional Context**
- Issue affects Line 6-9 volume retention
- Particularly impacts organizations doing supplementals with volume changes
- Need save function or volume persistence mechanism
- Testing done under LCFS Org 9