TODO: Handle Error for Existing Branch on Word Submission

Nessuno ha ancora preso questa issue.

When a user submits a new word or edits an existing word in the dictionary, the system should check if the branch already exists before attempting to create a new branch. Currently, if a branch with the same name already exists, the submission process fails without providing a clear error message to the user.

https://github.com/babblebey/jargons.dev/blob/0eeb366b4346c28a400586082fadb331c0ee342f/src/lib/branch.js#L10

**Proposed Solution:**
1. Add a check in the submission process to verify if the branch already exists. (but this will assume that a fork has already been created before-hand)
2. If the branch exists, display a user-friendly error message indicating that the word already exists in the dictionary.
3. Provide guidance on how to proceed, such as editing the existing word instead of creating a new one.

**Additional Notes:**
- Important to state that the proposed solution is pretty much me thinking out loud, I have some thought which really looks like it will change how/when we fork in order to address this in the way I am thinking about
- Its also important to know how/when we fork too, I can shed more lights on this

Inizia da src/lib/branch.js, intorno alla riga 10, e segui il flusso di invio delle parole, incluso il momento in cui vengono creati il fork e la branch. Determina come viene rilevata una branch esistente e come l'invio segnala attualmente il fallimento. Il lavoro è completato quando gli invii duplicati ricevono un messaggio chiaro che indirizza gli utenti a modificare la parola esistente, avendo compreso il momento della creazione del fork.

Scritto dal modello di indicizzazione a partire dal testo della issue.