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/types.ts

@@ -0,0 +1,107 @@
+// Mirrors api/internal/state.Snapshot. Keep field names aligned; the
+// Go side is authoritative.
+
+export type PoolStats = {
+  start: number;
+  update: number;
+  workers: number;
+  users: number;
+  disconnected: number;
+  shares: number;
+  accepted: number;
+  rejected: number;
+  dsps1: number;
+  dsps5: number;
+  dsps15: number;
+  dsps60: number;
+  dsps360: number;
+  dsps1440: number;
+  dsps10080: number;
+};
+
+export type User = {
+  user: string;
+  id: number;
+  workers: number;
+  bestdiff: number;
+  bestever: number;
+  dsps1: number;
+  dsps5: number;
+  dsps60: number;
+  dsps1440: number;
+  dsps10080: number;
+  lastshare: number;
+};
+
+export type Worker = {
+  user: string;
+  worker: string;
+  id: number;
+  dsps1: number;
+  dsps5: number;
+  dsps60: number;
+  dsps1440: number;
+  lastshare: number;
+  bestdiff: number;
+  bestever: number;
+  mindiff: number;
+  idle: boolean;
+};
+
+export type StratumClient = {
+  id: number;
+  enonce1: string;
+  diff: number;
+  dsps1: number;
+  dsps5: number;
+  dsps60: number;
+  dsps1440: number;
+  lastshare: number;
+  starttime: number;
+  address: string;
+  subscribed: boolean;
+  authorised: boolean;
+  idle: boolean;
+  useragent: string;
+  workername: string;
+  userid: number;
+  bestdiff: number;
+};
+
+export type BlockchainInfo = {
+  chain: string;
+  blocks: number;
+  headers: number;
+  bestblockhash: string;
+  difficulty: number;
+  mediantime: number;
+  verificationprogress: number;
+  initialblockdownload: boolean;
+};
+
+export type BlockRecord = {
+  height: number;
+  hash?: string;
+  reward_btc?: number;
+  found_at: string; // RFC 3339
+  source: string;
+};
+
+export type Snapshot = {
+  generated_at: string;
+  pool: PoolStats | null;
+  uptime_seconds: number;
+  users: User[] | null;
+  workers: Worker[] | null;
+  clients: StratumClient[] | null;
+  hashrate_hs_1m: number;
+  hashrate_hs_5m: number;
+  hashrate_hs_1h: number;
+  hashrate_hs_24h: number;
+  chain: BlockchainInfo | null;
+  network_hashrate_hs: number;
+  recent_blocks?: BlockRecord[];
+  ckpool_ok: boolean;
+  bitcoin_ok: boolean;
+  last_error?: string;
+};