💡 Add "Not Voted" Option for SPOs on Governance Action Details Page

### Area

Proposal Pillar

### Is there new design needed?

No

### What?

On the **Governance Action Details** page, the **"Not Voted"** option is currently displayed for:
- **DReps** (showing ADA value)
- **Constitutional Committee (CC) voters** (showing numbers)

However, **SPOs** do not have a **"Not Voted"** option displayed. This should be added to ensure consistency across all voter groups. The **SPO "Not Voted"** option should display the ADA value of uncast votes.

### Why?

- Ensures UI consistency across all voter groups.
- Provides clear visibility into uncast votes for SPOs, similar to DReps.
- Helps users better understand voting participation levels.
- Aligns governance action details with expected behavior.

### How?

- Identify where the **"Not Voted"** section is rendered for DReps and CC voters.
- Extend this functionality to **SPOs**, ensuring it displays the **ADA value** of uncast votes.
- Validate that the displayed data correctly reflects voting status.
- Ensure UI remains clean and readable with the additional information.

### (Optional) User Story with acceptance criteria

- [ ] The **"Not Voted"** option is displayed for SPOs on the Governance Action Details page.
- [ ] The ADA value of uncast votes is shown for SPOs.
- [ ] DReps and CC voters continue to display their respective "Not Voted" data correctly.
- [ ] UI is consistent and properly formatted.