Other sharing options

### Feature summary

Add more sharing options beyond secret gists

### What problem are you trying to solve?

Can we have some other sharing options besides secret gists? My account is an enterprise managed account and we are not allowed to create gists of any kind, but there are many times I will want to share a session with a coworker. I would like some other way to share a conversation rather than trying to copy the contents and then edit the formatting.

### Proposed solution

An option to copy a markdown-formatted conversation, or a plaintext conversation, or a way to save a session to a file. I know the CLI has several more sharing options but the app version only has gists and /share doesn't work.

### Workflow impact

_No response_

### Installation context

_No response_

### Additional context

_No response_

Inizia esaminando il flusso attuale di condivisione dei Gist dell’app e confrontandolo con le opzioni di condivisione esistenti della CLI. Determina quale opzione diversa da Gist—Markdown, testo normale o salvataggio di una sessione in un file—rientra nell’ambito, quindi verifica che il workflow scelto supporti gli account gestiti dall’azienda ed eviti la modifica manuale delle copie.

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