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/app.css

@@ -0,0 +1,151 @@
+:root {
+  color-scheme: dark light;
+  --bg: #0b0e14;
+  --bg-alt: #11151d;
+  --bg-card: #151a24;
+  --bg-hover: #1c2230;
+  --border: #232a3a;
+  --fg: #e6e9ef;
+  --fg-dim: #8a92a6;
+  --accent: #ff7a3a;
+  --accent-dim: #b8501f;
+  --good: #5ce0a8;
+  --bad: #ff6b6b;
+  --warn: #f5c447;
+  font-family: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
+  font-size: 14px;
+  line-height: 1.5;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+* {
+  box-sizing: border-box;
+}
+
+html,
+body {
+  margin: 0;
+  padding: 0;
+  background: var(--bg);
+  color: var(--fg);
+  min-height: 100vh;
+}
+
+body {
+  font-variant-numeric: tabular-nums;
+}
+
+a {
+  color: var(--accent);
+  text-decoration: none;
+}
+a:hover {
+  text-decoration: underline;
+}
+
+button {
+  font: inherit;
+  color: inherit;
+  background: var(--bg-card);
+  border: 1px solid var(--border);
+  padding: 0.5em 1em;
+  border-radius: 6px;
+  cursor: pointer;
+}
+button:hover {
+  background: var(--bg-hover);
+}
+
+code,
+.mono {
+  font-family: "JetBrains Mono", "Fira Code", ui-monospace, SFMono-Regular,
+    Menlo, monospace;
+  font-size: 0.92em;
+}
+
+.card {
+  background: var(--bg-card);
+  border: 1px solid var(--border);
+  border-radius: 10px;
+  padding: 1.25rem 1.5rem;
+}
+
+.grid {
+  display: grid;
+  gap: 1rem;
+}
+
+.grid-4 {
+  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
+}
+.grid-2 {
+  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
+}
+
+.stat-label {
+  color: var(--fg-dim);
+  font-size: 0.85em;
+  text-transform: uppercase;
+  letter-spacing: 0.04em;
+  margin-bottom: 0.35em;
+}
+.stat-value {
+  font-size: 1.7rem;
+  font-weight: 600;
+  letter-spacing: -0.01em;
+}
+.stat-sub {
+  color: var(--fg-dim);
+  font-size: 0.85em;
+  margin-top: 0.25em;
+}
+
+table {
+  width: 100%;
+  border-collapse: collapse;
+}
+th,
+td {
+  text-align: left;
+  padding: 0.55rem 0.85rem;
+  border-bottom: 1px solid var(--border);
+}
+th {
+  font-weight: 500;
+  color: var(--fg-dim);
+  font-size: 0.82em;
+  text-transform: uppercase;
+  letter-spacing: 0.04em;
+}
+tbody tr:hover {
+  background: var(--bg-hover);
+}
+td.num,
+th.num {
+  text-align: right;
+}
+
+.badge {
+  display: inline-block;
+  padding: 0.15em 0.55em;
+  border-radius: 999px;
+  font-size: 0.75em;
+  border: 1px solid var(--border);
+  background: var(--bg-alt);
+}
+.badge.good {
+  color: var(--good);
+  border-color: #2f5c48;
+  background: #0f2419;
+}
+.badge.bad {
+  color: var(--bad);
+  border-color: #5c2f2f;
+  background: #241010;
+}
+.badge.warn {
+  color: var(--warn);
+  border-color: #5c502f;
+  background: #241f10;
+}