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)

api/cmd/kamado-api/main.go

@@ -128,6 +128,7 @@ func main() {
 	go tailer.Run(ctx)
 	go agg.IngestBlockEvents(ctx, tailer.Events)
 	go agg.IngestAttemptEvents(ctx, tailer.Attempts)
+	go agg.IngestLatencyEvents(ctx, tailer.Latencies)
 
 	srv := &http.Server{
 		Addr:              cfg.ListenAddr,