Function handle_update_workspace_meta 

pub(super) fn handle_update_workspace_meta(
    state: &mut State,
    workspace_id: String,
    meta_patch: Value,
) -> Vec<Event>

Phase E.5.3 — pass-through validation + emit for workspace meta updates. The reducer does NOT mutate meta in state (it doesn’t track meta in WorkspaceRecord); the persist subscriber applies the patch directly to wstore. This keeps the reducer’s state shape unchanged while still routing every meta mutation through the broadcast bus for observers.