Function hashes_in_note

pub fn hashes_in_note(contents: &str) -> HashSet<String>

Every commit hash already recorded as a row in a day note.

The hash is the row’s last column, and a commit id contains no |, so the text after the final separator is read directly. Anything that is not plausibly an object id — the table header, the |---| rule, a stray line — is dropped, which is what keeps COMMIT HASH out of the set.