Ability to work with ephemeral / throwaway files (and not have them added to Collections by default)

We need the ability to work with temporary files without them automatically being saved to our Collections system. This would be particularly useful for quick file sharing and temporary work sessions.

Currently, when we upload any file in-thread, it gets automatically added to our Collection. Instead, we'd like:

• Files uploaded in-thread should remain ephemeral by default

• The file change unit should display an option to manually save it to the collection when desired

This would give us more control over what gets permanently stored versus what's just temporary working material. We often share quick screenshots, drafts, or reference files that don't need to clutter our organized Collections.