sc ws fork --author is stored in the session manifest but harvest ignores it (help text says harvest uses it) #286

Found by the docs sync (#284). sc ws fork --author is recorded in the session manifest and its --help says harvest uses it, but ws_harvest calls resolve_author(<harvest --author>) and ignores the stored value. Either use the stored author as the default when harvest is given none (preferred, matches the help text) or drop the fork flag/help text; add a test; update the skill reference and CLAUDE.md wording accordingly.