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/dashboard_events.rs

@@ -26,6 +26,7 @@
 use serde::Serialize;
 
 use crate::container_view::ContainerView;
+use crate::dashboard::{MetaInputView, TombstoneView};
 
 #[derive(Debug, Clone, Serialize)]
 #[serde(rename_all = "snake_case", tag = "kind")]
@@ -156,4 +157,25 @@ pub enum DashboardEvent {
     /// `nixos-container destroy` (operator-driven or otherwise) on the
     /// next rescan.
     ContainerRemoved { seq: u64, name: String },
+    /// Full snapshot of the tombstones list. Emitted on every
+    /// mutation that could add / remove a tombstone: destroy
+    /// (with or without purge), purge-tombstone, spawn approval
+    /// (which can consume a tombstone of the same name). Snapshot
+    /// shape (not diff) because the list is tiny (single-digit
+    /// typical) and recomputing avoids the add/remove races a
+    /// per-row event would have.
+    TombstonesChanged {
+        seq: u64,
+        tombstones: Vec<TombstoneView>,
+    },
+    /// Full snapshot of `meta/flake.lock`'s root inputs. Emitted
+    /// after every operation that bumps a lock: `meta-update`,
+    /// `rebuild_agent` (lock bumps via two-phase staging),
+    /// `update-all`. Same snapshot-shape rationale as
+    /// `TombstonesChanged` — the list is small (one row per agent
+    /// plus their fetched inputs).
+    MetaInputsChanged {
+        seq: u64,
+        inputs: Vec<MetaInputView>,
+    },
 }