feat: hand recorder v1 (tap-to-build, overlay) — recorder steps 2-4

Tap-to-build hand recorder per docs/RECORDER.md. Correctness by construction: every
tap writes a known value into a known slot, emitting the canonical structured contract
(server normalize_structured() is the shape authority, so the client is best-effort).

- recorder.js: mount-agnostic module (mounts into any container -> overlay now,
  standalone later, zero logic change). Pure buildStructured(state)->contract dict.
  Card picker: sticky-suit-or-rank-first + x (unknown suit) + unknown-card; lock resets
  per slot so it never bleeds between cards. Pre-fills from /session/data (stakes->blinds,
  stack->hero, villains->seated). Per-street action entry, manual street advance.
- recorder.css: full-screen overlay using app theme tokens; floating launcher.
- index.html: overlay div + script + launcher (chat/session stays mounted underneath).

Validated end-to-end: JS core builds a hand (sticky/rainbow/unknown cards all correct)
-> POST /hands -> normalized -> /hand/{id} replay round-trips identically.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyra/web/static/index.html

@@ -4,6 +4,7 @@
   <meta charset="UTF-8" />
   <title>Lyra Core Chat</title>
   <link rel="stylesheet" href="style.css" />
+  <link rel="stylesheet" href="/recorder.css" />
   <!-- PWA -->
   <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, viewport-fit=cover" />
   <meta name="mobile-web-app-capable" content="yes" />
@@ -1245,5 +1246,28 @@
     });
   </script>
   <script src="/nav.js"></script>
+  <!-- Hand recorder (overlay; chat/session stays mounted underneath) -->
+  <div id="recorderOverlay" class="rec-overlay"></div>
+  <script src="/recorder.js"></script>
+  <script>
+    (function () {
+      var btn = document.createElement("button");
+      btn.id = "recLaunch";
+      btn.textContent = "＋ Hand";
+      btn.title = "Record a hand";
+      document.body.appendChild(btn);
+      var overlay = document.getElementById("recorderOverlay");
+      function close() { overlay.classList.remove("open"); overlay.innerHTML = ""; }
+      btn.addEventListener("click", function () {
+        overlay.innerHTML = "";
+        overlay.classList.add("open");
+        var sid = window.currentSession;
+        window.Recorder.mount(overlay, {
+          onClose: close,
+          onSave: function (id) { close(); window.open("/hand/" + id, "_blank"); }
+        });
+      });
+    })();
+  </script>
 </body>
 </html>