Update Swedish translations in sv.js

[JessicaFredin]

This pull request adds missing Swedish translations to the sv.js file as outlined in Issue #852.

Changes Made:

• Replaced all undefined values with accurate Swedish translations.
• Verified that the translations are culturally appropriate and match the intended meaning of the English text.
• Preserved placeholders like %strong% in the translated text.
• For the plural_suffix key, left the value as an empty string ("") because Swedish pluralization is context-dependent and varies (e.g., "or", "ar", "er", "en", or no suffix). This requires contextual handling elsewhere in the application.

Closes #852

[CLAassistant]

All committers have signed the CLA.

[jelveh]

Hi @JessicaFredin could you look into the CLA before I can review and merge your PR? Thank you.