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/App.svelte

@@ -11,6 +11,7 @@
   import BestShares from "./lib/BestShares.svelte";
   import UserDetailPage from "./lib/UserDetailPage.svelte";
   import WorkerDetailPage from "./lib/WorkerDetailPage.svelte";
+  import SharesBar from "./lib/SharesBar.svelte";
   import BlockFoundAnimation from "./lib/BlockFoundAnimation.svelte";
 
   onMount(() => {
@@ -39,6 +40,7 @@
     <UserDetailPage />
   {:else}
     <PoolOverview />
+    <SharesBar />
     <HashrateChart />
     <BlocksTable />
     <BestShares />