Managing mutable files

[ErikBjare]

Right now files are stored by path in the conversation log, this makes the content mutable and incorrectly modifies past messages when changes to the files have been made.

• Attached files are mutable and their conversation state not preserved: If a file is referenced, we can only read the most recent version.
  • Could be solved by storing referenced files in log dir, perhaps named f"{name}-{hash or version}.{ext}" (something content/version-addressed)