[Feature Request]: Update locales with missing language translations

### 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

Some JSON locales files on MPM i.e `src/frontend/src/assets/locales/fr.json`, pt.json, have missing translations. Below is a snippet from our french translation file (`fr.json`) which still contains text with english.

```json
{
"errors": {
"alreadyUsedCompanyEmail": "Company with email already exists",
"alreadyUserAdminEmail": "Admin Owner with email already exists"
},
"menu": {
"Agents": "Agents",
"Angaza SHS": "Angaza SHS",
"Appliances": "Appliances",
"Asset Types": "Asset Types",
"Bulk Registration": "Bulk Registration",
...
```

It would be nice if all the locale JSON files are properly translated to their respective languages.

### Proposed Solution

Only translate keys that do not have a translation; preserve already translated keys.

### Alternatives Considered

N/A

### Additional Information

_No response_

Review the locale files under src/frontend/src/assets/locales/, starting with fr.json and pt.json, and compare their keys and existing translations. Translate only values that still contain English while preserving completed translations; done means the affected locale files contain translations for all currently untranslated keys.

Written by the indexing model from the issue text.