Phase 3: Svelte 5 UI skeleton

Svelte 5 + Vite + TypeScript dashboard that consumes kamado-api over
REST for the first paint and then subscribes to /api/ws for live
updates. Zero runtime deps beyond svelte itself; plain CSS, no
component library.

Layout:

- Header with brand, WebSocket status badge, chain + height
- PoolOverview: hashrate (1m/5m/1h/24h), miner count, network
  hashrate + diff, pool share (ppb), expected time to block, uptime
- BlocksTable: recent solves from the in-memory ring (will be
  SQLite-backed in Phase 2b.5)
- BestShares: top-10 workers by bestever, falling back to bestdiff
  when the ckpool patch isn't present
- MinersTable: joined view of stratum clients and workers with
  user-agent-based hardware detection (Bitaxe, NerdQAxe, Antminer,
  ...), hashrate, best-round, best-ever, last share

State is a single $state() snapshot store in svelte-runes form;
components read from it via $derived. The store does one initial
REST snapshot fetch, then owns the WebSocket with exponential
backoff reconnects.

Vite dev server on :5173 proxies /api and /api/ws to localhost:8080
so you can run `make ui-dev` alongside `make up` in development.
Production serving (bundled into the Go binary via embed, behind /
on :8080) lands in Phase 4.

ui/src/lib/BlocksTable.svelte

@@ -0,0 +1,56 @@
+<script lang="ts">
+  import { snap } from "../stores/snapshot.svelte";
+  import { formatAgo } from "../format";
+
+  const blocks = $derived.by(() => {
+    const b = snap.data?.recent_blocks ?? [];
+    // Show newest first.
+    return [...b].reverse();
+  });
+</script>
+
+<section class="card">
+  <h2>Blocks found</h2>
+  {#if blocks.length === 0}
+    <div class="empty">
+      No blocks found yet. Any solve will appear here instantly via the
+      log tailer, and persist to SQLite once Phase 2b.5 ships.
+    </div>
+  {:else}
+    <table>
+      <thead>
+        <tr>
+          <th>Height</th>
+          <th>Hash</th>
+          <th class="num">When</th>
+          <th>Source</th>
+        </tr>
+      </thead>
+      <tbody>
+        {#each blocks as b (b.height + "-" + b.found_at)}
+          <tr>
+            <td class="mono">{b.height}</td>
+            <td class="hash mono">{b.hash ? b.hash.slice(0, 16) + "…" : "—"}</td>
+            <td class="num">{formatAgo(new Date(b.found_at).getTime() / 1000)}</td>
+            <td>{b.source}</td>
+          </tr>
+        {/each}
+      </tbody>
+    </table>
+  {/if}
+</section>
+
+<style>
+  h2 {
+    margin: 0 0 1rem;
+    font-size: 1.05rem;
+    font-weight: 600;
+  }
+  .empty {
+    color: var(--fg-dim);
+    padding: 0.5rem 0;
+  }
+  .hash {
+    color: var(--fg-dim);
+  }
+</style>