Add spanish translations

[sandraR01]

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What changes I've made

This PR completes all missing Spanish translations across the entire project — backend, frontend, and email templates.

Why I've made these changes

Because we found out that the project has missing translations into Spanish

How I've tested these changes

Checking if appears in Spanish

Checklist

• I have read the contributing guidelines.
• My code follows the coding standards of the project.
• I have tested my changes, and they work as expected.
• I understand that this PR will be closed if I do not follow the contributor guidelines and if this PR template is left unedited.

I have read the CLA Document and I hereby sign the CLA

[github-actions]

All contributors have signed the CLA ✍️ ✅
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[sandraR01]

I have read the CLA Document and I hereby sign the CLA