dashboard: tombstones + meta_inputs events — last /api/state refetches drop

new DashboardEvent::TombstonesChanged + MetaInputsChanged carry
full snapshots (lists are tiny; snapshot beats diff for race
avoidance). Coordinator-side helpers
emit_tombstones_snapshot + emit_meta_inputs_snapshot fire from
every mutation site: actions::destroy + post_purge_tombstone +
actions::approve (spawn finalise consumes tombstone) +
run_meta_update + auto_update::rebuild_agent (lock bumps).

client adds derived stores + apply* handlers + drops the
post-submit refetch on PURG3 (container row + tombstone row)
and meta-update.

after this commit /api/state is fetched exactly once per page
session (cold load); every other change rides the SSE channel.

hive-c0re/src/auto_update.rs

@@ -99,6 +99,8 @@ pub async fn rebuild_agent(coord: &Arc<Coordinator>, name: &str, current_rev: &s
             // shifted — rescan so dashboards drop the "needs update"
             // chip without waiting for the next /api/state poll.
             coord.rescan_containers_and_emit().await;
+            // Lock bump → meta-inputs panel needs to re-render.
+            crate::dashboard::emit_meta_inputs_snapshot(coord);
         }
         Err(e) => {
             coord.notify_manager(&hive_sh4re::HelperEvent::Rebuilt {