maybe a prototype, maybe it will go in production

S008: edits, owner moderation, move traces, inline hashtags master

- edit/delete commands: own posts always; any post as space owner (zds authority override) - move leaves a trace message in the old thread naming the target - tags live only as inline hashtags in text (per design revision): thread.tags removed, records keep raw text; read --tag surfaces threads containing a tagged message (core/hashtag.zig) - scenario-space extended: edits, owner powers, tag search, denials