Request for Manual Save as well as Auto Save

There is a request in #4792395-zen saying: Please give the option to "auto save note" or "manual save note" in the settings, it's very useful when we make a typo, or when something goes wrong and we don't save and want to restore back to the original post again before editing.

The issue identifies settings and note editing as the scope, but names no files or tests. Begin by mapping where save behavior and settings are implemented, then confirm the intended manual-save and restoration semantics with maintainers. Done should be an agreed, tested setting that switches between auto and manual saving.

Written by the indexing model from the issue text.