Revamp dashboard and persist pool stats across restarts

Dashboard now renders 10 tiles in a 5x2 overview: hashrate, best
share, miners, network hashrate, and expected block on the top row;
difficulty, block height, block reward, total work, and the
difficulty-adjustment countdown on the bottom row. Difficulty is
rendered with T/P suffixes instead of scientific notation, the main
hashrate card shows the 1-minute value, and the block-height tile
pulses orange when the network tip advances.

Added a 24-hour hashrate area chart below the overview, sampled
once per minute. Samples are persisted to a new hashrate_samples
SQLite table and restored on startup so the chart doesn't reset
every time kamado-api is restarted.

Cumulative pool work (sum of accepted diff-1-normalized shares) is
now tracked across ckpool restarts. The aggregator integrates only
positive deltas on pool.Shares — a regression means ckpool's
counter reset to zero and the baseline is refreshed without losing
the running total. A hasPoolSharesBaseline flag prevents double-
counting on the first refresh after a kamado-api restart. The
value is persisted to a new kv table once per minute.

Next-block reward (subsidy + fees) is fetched from bitcoind
getblocktemplate at most once per minute and surfaced as a tile.

Header's block-height badge now reads prevHeight via untrack() so
the effect doesn't form a dependency cycle with its own write.

ui/src/lib/PoolOverview.svelte

@@ -1,8 +1,11 @@
 <script lang="ts">
+  import { untrack } from "svelte";
   import { snap } from "../stores/snapshot.svelte";
   import {
     formatHashrate,
     formatUptime,
+    formatDifficulty,
+    formatWork,
     expectedBlockSeconds,
     formatDuration,
   } from "../format";
@@ -10,31 +13,69 @@
   const data = $derived(snap.data!);
   const miners = $derived(data.clients?.length ?? 0);
   const workerCount = $derived(data.workers?.length ?? 0);
+  const height = $derived(data.chain?.blocks ?? 0);
 
-  // Pool share of the network hashrate, used both for display and for
-  // the expected-block calculation. Network diff comes from bitcoind.
   const poolShare = $derived.by(() => {
     const net = data.network_hashrate_hs;
     if (!net || net <= 0) return 0;
-    return data.hashrate_hs_1h / net;
+    return data.hashrate_hs_1m / net;
   });
 
   const expected = $derived.by(() => {
     const diff = data.chain?.difficulty ?? 0;
-    return expectedBlockSeconds(data.hashrate_hs_1h, data.network_hashrate_hs, diff);
+    return expectedBlockSeconds(data.hashrate_hs_1m, data.network_hashrate_hs, diff);
+  });
+
+  const effort = $derived.by(() => {
+    if (!isFinite(expected) || expected <= 0) return 0;
+    const uptime = data.uptime_seconds;
+    if (!uptime || uptime <= 0) return 0;
+    return (uptime / expected) * 100;
+  });
+
+  const retarget = $derived.by(() => {
+    if (!height) return { progress: 0, remaining: 2016, eta: "" };
+    const inEpoch = height % 2016;
+    const remaining = 2016 - inEpoch;
+    const progress = (inEpoch / 2016) * 100;
+    const etaSec = remaining * 600;
+    return { progress, remaining, eta: formatDuration(etaSec) };
+  });
+
+  // Total hashes done by the pool = cumulative_shares * 2^32.
+  const totalHashes = $derived(data.cumulative_shares * 2 ** 32);
+
+  // Block-height flash on network-wide new block.
+  let prevHeight = $state(0);
+  let heightFlash = $state(false);
+  $effect(() => {
+    const h = height;
+    const prev = untrack(() => prevHeight);
+    if (h > 0 && prev > 0 && h !== prev) {
+      heightFlash = true;
+      setTimeout(() => { heightFlash = false; }, 1800);
+    }
+    prevHeight = h;
   });
 </script>
 
-<section class="grid grid-4">
+<section class="grid grid-5">
+  <!-- Row 1 -->
   <div class="card">
-    <div class="stat-label">Hashrate (1h)</div>
-    <div class="stat-value">{formatHashrate(data.hashrate_hs_1h)}</div>
+    <div class="stat-label">Hashrate</div>
+    <div class="stat-value">{formatHashrate(data.hashrate_hs_1m)}</div>
     <div class="stat-sub">
-      1m {formatHashrate(data.hashrate_hs_1m)} · 5m {formatHashrate(data.hashrate_hs_5m)}
+      5m {formatHashrate(data.hashrate_hs_5m)} · 1h {formatHashrate(data.hashrate_hs_1h)}
       · 24h {formatHashrate(data.hashrate_hs_24h)}
     </div>
   </div>
 
+  <div class="card">
+    <div class="stat-label">Best share</div>
+    <div class="stat-value">{formatDifficulty(data.best_diff)}</div>
+    <div class="stat-sub">all-time pool record</div>
+  </div>
+
   <div class="card">
     <div class="stat-label">Miners</div>
     <div class="stat-value">{miners}</div>
@@ -45,14 +86,102 @@
     <div class="stat-label">Network</div>
     <div class="stat-value">{formatHashrate(data.network_hashrate_hs)}</div>
     <div class="stat-sub">
-      diff {data.chain?.difficulty.toExponential(2) ?? "—"} ·
-      share {(poolShare * 1e9).toFixed(2)} ppb
+      pool share {(poolShare * 1e9).toFixed(2)} ppb
     </div>
   </div>
 
   <div class="card">
     <div class="stat-label">Expected block</div>
     <div class="stat-value">{formatDuration(expected)}</div>
-    <div class="stat-sub">uptime {formatUptime(data.uptime_seconds)}</div>
+    <div class="stat-sub">
+      effort {effort.toFixed(1)}% · uptime {formatUptime(data.uptime_seconds)}
+    </div>
+  </div>
+
+  <!-- Row 2 -->
+  <div class="card">
+    <div class="stat-label">Difficulty</div>
+    <div class="stat-value">{formatDifficulty(data.chain?.difficulty ?? 0)}</div>
+    <div class="stat-sub">network target</div>
+  </div>
+
+  <div class="card height-card" class:new-block={heightFlash}>
+    <div class="stat-label">Block height</div>
+    <div class="stat-value">{height ? height.toLocaleString() : "—"}</div>
+    <div class="stat-sub">{data.chain?.chain ?? "—"}</div>
+  </div>
+
+  <div class="card">
+    <div class="stat-label">Block reward</div>
+    <div class="stat-value">
+      {data.next_block_reward_btc ? data.next_block_reward_btc.toFixed(4) : "—"}
+      <span class="unit">BTC</span>
+    </div>
+    <div class="stat-sub">subsidy + fees (next block)</div>
+  </div>
+
+  <div class="card">
+    <div class="stat-label">Total work</div>
+    <div class="stat-value">{formatWork(totalHashes)}</div>
+    <div class="stat-sub">hashes submitted by pool</div>
+  </div>
+
+  <div class="card">
+    <div class="stat-label">Diff adjustment</div>
+    <div class="stat-value">{retarget.remaining} blocks</div>
+    <div class="stat-sub">
+      <div class="retarget-bar">
+        <div class="retarget-fill" style="width:{retarget.progress}%"></div>
+      </div>
+      <span>{retarget.progress.toFixed(1)}% · ~{retarget.eta}</span>
+    </div>
   </div>
 </section>
+
+<style>
+  .grid-5 {
+    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
+  }
+  .retarget-bar {
+    height: 4px;
+    background: var(--border);
+    border-radius: 2px;
+    overflow: hidden;
+    margin-bottom: 0.35em;
+  }
+  .retarget-fill {
+    height: 100%;
+    background: var(--accent);
+    border-radius: 2px;
+    transition: width 0.5s ease;
+  }
+  .unit {
+    font-size: 0.65em;
+    color: var(--fg-dim);
+    font-weight: 400;
+    margin-left: 0.15em;
+  }
+  .height-card {
+    transition: box-shadow 0.3s, border-color 0.3s;
+  }
+  .height-card.new-block {
+    animation: height-flash 1.8s ease-out;
+  }
+  @keyframes height-flash {
+    0% {
+      border-color: var(--accent);
+      box-shadow: 0 0 0 2px var(--accent), 0 0 32px rgba(255, 122, 58, 0.55);
+      transform: scale(1.03);
+    }
+    40% {
+      border-color: var(--accent);
+      box-shadow: 0 0 0 1px var(--accent), 0 0 20px rgba(255, 122, 58, 0.35);
+      transform: scale(1);
+    }
+    100% {
+      border-color: var(--border);
+      box-shadow: none;
+      transform: scale(1);
+    }
+  }
+</style>