Add web shell, build and deploy scripts, Playwright smoke

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

web/main.js

@@ -0,0 +1,58 @@
+// Streams the wasm, runs Go, shows crashes.
+const stderr = []
+const write = globalThis.fs.writeSync.bind(globalThis.fs)
+globalThis.fs.writeSync = (fd, buf) => {
+  if (fd === 2) stderr.push(new TextDecoder().decode(buf))
+  return write(fd, buf)
+}
+
+function crash (msg) {
+  const why = [msg, stderr.join('').slice(-4000)].filter(Boolean).join('\n\n')
+  console.error('crychic: crash', why)
+  document.getElementById('why').textContent = why
+  document.getElementById('over').hidden = false
+}
+document.getElementById('reload').onclick = () => location.reload()
+
+async function load () {
+  const t0 = performance.now()
+  const res = await fetch('__WASM__')
+  if (!res.ok) throw new Error(`${res.url}: HTTP ${res.status}`)
+  const total = Number('__SIZE__')
+  const reader = res.body.getReader()
+  const parts = []
+  let got = 0
+  for (;;) {
+    const { done, value } = await reader.read()
+    if (done) break
+    parts.push(value)
+    got += value.length
+    const pct = Math.min(100, Math.floor(got / total * 100))
+    document.getElementById('fill').style.width = pct + '%'
+    document.getElementById('loading').setAttribute('aria-valuenow', pct)
+  }
+  const bytes = new Uint8Array(got)
+  let off = 0
+  for (const p of parts) {
+    bytes.set(p, off)
+    off += p.length
+  }
+  const go = new Go()
+  const { instance } = await WebAssembly.instantiate(bytes, go.importObject)
+  go.run(instance).then(() => crash('The Go program exited.'), (err) => crash(String(err && err.stack || err)))
+  await new Promise((resolve, reject) => {
+    const until = performance.now() + 30000
+    const poll = () => {
+      if (window.__crychic?.ready) return resolve()
+      if (performance.now() > until) return reject(new Error('No frame within 30 s.'))
+      requestAnimationFrame(poll)
+    }
+    poll()
+  })
+  const first = Math.round(performance.now() - t0)
+  document.getElementById('loading').remove()
+  window.__crychicBoot = { wasm: '__WASM__', bytes: got, first }
+  console.info(`crychic: wasm ${(got / 1e6).toFixed(1)} MB, first frame ${first} ms`)
+}
+
+load().catch((err) => crash(String(err && err.stack || err)))