[Feature Request]: Rename MiniGrid References to Sites on UI (frontend only)

### Preflight Checklist

- [x] I have read the [Contributing Guidelines](https://github.com/EnAccess/micropowermanager/blob/main/CONTRIBUTING.md) for this project, if it exists.
- [x] I agree to follow the [Code of Conduct](https://github.com/EnAccess/micropowermanager/blob/main/CODE_OF_CONDUCT.md) that this project adheres to.
- [x] I have searched the [issue tracker](https://github.com/EnAccess/micropowermanager/issues) for a feature request that matches the one I want to file, without success.

### Problem Description

Rename MiniGrid references on the UI to Sites on the frontend codebase, this should only apply on the frontend. Other code changes i.e endpoint naming, field names etc, will remain untouched.

Sub-issue to #1363 to land in MPMv1.

### Proposed Solution

N/A

### Alternatives Considered

N/A

### Additional Information

_No response_