Update messages.po in Catalan

[aryiu]

Fixed and improved some Catalan strings:

• "starter pack" → "paquet inicial", to avoid anglicisms.
• "informar" → "denunciar", changed to avoid ambiguity. I think "denunciar" could be a better choice since it's a more specific term, while "informar" can be too general.
• Fixed the use of "tu" instead of "vos", to maintain the same voice in all strings.
• Added some "el dia" in strings with dates, for a better sense in Catalan. For example,Arxivat del dia 11 d'octubre, 2024 instead of Arxivat de 11 d'octubre, 2024
• Added ":" when a name follows, to avoid wrong apostrophization. For example,Paquet inicial de: Andreu instead of Paquet inicial de Andreu. If it is the handle, I think this should be the same, because the "@" symbol is called "arroba" and should be apostrophed, so I think it's better to add a ":" before it.