Option to SAVE all Chats LOCALLY so that all not lost if server goes down dies gets hacked etc

### Your use case

#### What would you like to do?
Apologies if somehow this is already possible through some option in DESKTOP Element that I wasn't aware of, if so please let me know how to enable Local Saving of all conversations and attachments etc.

#### Why would you like to do it?
I use DESKTOP Element and would like to not worry about losing data/rooms/conversations if the server goes down, crashes, or gets hacked, wiped or anything like that. I want the CLIENT Desktop Element app to always SAVE everything Locally.

#### How would you like to achieve it?
I would like a Global Option to "Save All Locally", and/or perhaps "per room" setting as well.

### Have you considered any alternatives?

I could not see any better other alternatives to saving all locally on Desktop Element.

### Additional context

_No response_

The issue does not identify any files, tests, or entry points. Start by locating the desktop client's conversation and attachment persistence code, then determine the scope of a global or per-room local-save option and define completion around preserving all requested chats and attachments through server loss.

Written by the indexing model from the issue text.