serialize called tagsOf per rid and resolveName per symbol, each a full tagxref scan -- O(rids x rows) and O(symbols x rows). A one-check-in append cost the next reader 42s on a 42K-check-in store (#107); now 0.8s, and a full derive drops 74s to 21s.

tagsOf routes through the existing rid_tags index; resolveName gets the inverse tag_rids index, maintained by the same helper pair so the two stay precise together. Selection semantics unchanged. check-in: 0aa75ac13d user: dmestas tags: trunk