feat(voice): 实时语音对话页（React 完全复刻原版 UI）

- /voice 页面：中间圆球 + 左右按钮 + 状态图标 + 右下角气泡（进场/淡出/阶梯字号/上限8）+ 噪声门弧线电平，结构类名与原版一致
- s2s WebSocket 客户端 + worklet 音频（mic-capture/audio-playback）+ orb 可视化
- 摄像头实时预览（默认开启）+ 视觉识别状态条（后端 YOLO 推理）
- 底部园区概览条（复用 ParkOverviewStrip），orb-wrap 视窗居中
- 页眉复用 ScreenLayout；左右键导航加入 /voice
- 文档：docs/voice-integration-plan.md

public/voice-demo/ws/codec.js

@@ -0,0 +1,57 @@
+// @ts-check
+/**
+ * Pure, stateless helpers for the WebSocket realtime client: base64 <-> PCM
+ * conversion for the audio frames on the wire, transcript extraction from a
+ * `response.done` payload, and a tiny URL helper. Kept separate from the client
+ * so the protocol/state logic stays readable.
+ */
+
+/** @param {string} url */
+export function trimTrailingSlash(url) {
+  return url.endsWith("/") ? url.slice(0, -1) : url;
+}
+
+/**
+ * Pull the assistant transcript out of a `response.done` payload. The text
+ * lives in `response.output[].content[].transcript` (audio) or `.text`. Used as
+ * the source of truth for interrupted replies, where the dedicated
+ * `*.transcript.done` event may never arrive.
+ * @param {any} response
+ * @returns {string}
+ */
+export function extractResponseTranscript(response) {
+  const output = response?.output;
+  if (!Array.isArray(output)) return "";
+  /** @type {string[]} */
+  const parts = [];
+  for (const item of output) {
+    for (const part of item?.content ?? []) {
+      const text = part?.transcript ?? part?.text;
+      if (typeof text === "string" && text.trim()) parts.push(text.trim());
+    }
+  }
+  return parts.join(" ").trim();
+}
+
+/** @param {ArrayBuffer} buf */
+export function base64FromArrayBuffer(buf) {
+  const bytes = new Uint8Array(buf);
+  // Chunked encoding so we don't blow up the call stack on long buffers.
+  let binary = "";
+  const chunk = 0x8000;
+  for (let i = 0; i < bytes.length; i += chunk) {
+    binary += String.fromCharCode.apply(null, /** @type {number[]} */ (
+      /** @type {unknown} */ (bytes.subarray(i, i + chunk))
+    ));
+  }
+  return btoa(binary);
+}
+
+/** @param {string} b64 */
+export function base64ToBytes(b64) {
+  const binary = atob(b64);
+  const len = binary.length;
+  const out = new Uint8Array(len);
+  for (let i = 0; i < len; i++) out[i] = binary.charCodeAt(i);
+  return out;
+}