Add block-update latency tracking, raw share counters, and shares bar UI

Log ZMQ→mining.notify latency in ckpool (patch 0005), expose a raw
reject counter (patch 0006), and surface both in the dashboard:

- Block latency card shows avg/last ms, wasted work, and block count
- SharesBar component shows session + all-time accepted/rejected with
  a Demon Slayer flame-slash animation on new shares
- Miners card info moved to MinersTable section header
- Latency stats and share counts persist across restarts via kv store
- Removed misleading pool-wide share stats from per-worker/user pages
  (ckpool doesn't expose per-user raw counts)

ui/src/lib/UserDetailPage.svelte

@@ -134,6 +134,7 @@
     };
   });
 
+
   const explorerBase = $derived(
     explorerBaseFor(snap.data?.chain?.chain, snap.data?.mempool_base_url),
   );
@@ -198,6 +199,7 @@
     </div>
   </section>
 
+
   <section class="card">
     <h3>Workers</h3>
     {#if workerRows.length === 0}