SCF.4 Last-writer rules for synced rows: newest wins, a content tie-break, a clock guard, three-way merge and kept replaced edits

super-merge.js and RowMerge.php share test vectors. Newest wins including deletions; an exact tie is decided by content so every copy agrees; a row more than five minutes ahead is refused; a device keeps the last synced row and merges different fields of one row; an unsynced edit that lost is kept with Restore. Server merges stay whole-row; the client merges before it pushes.