卫戍协议：盟约 web remake — initial import

Online co-op browser remake of Arknights' Stronghold Protocol: Alliance
(client-simulated combat, official waves/bonds/items/strategies, 3D board,
facing wheel, operator loadout, official emotes, deployment scripts).

public/js/ui/compat.js

@@ -0,0 +1,93 @@
+// Small polyfills for the older browsers the client supports (Safari / iOS 15.0–15.3, Firefox ESR, older Chromium on
+// Android tablets). Imported first by main.js (and the dev harnesses), so every later module — including the ones
+// loaded on demand (render engine, battle sim) — sees them. Each one is installed only when the browser lacks it
+// (feature detection, never UA sniffing) and is a faithful subset of the standard behaviour:
+//   Object.hasOwn                       Safari < 15.4, Firefox < 92
+//   Array/String/TypedArray .at()       Safari < 15.4, Firefox < 90
+//   Array .findLast / .findLastIndex    Safari < 15.4, Firefox < 104
+//   structuredClone                     Safari < 15.4, Firefox < 94 (JSON-safe values + Map/Set/Date; enough for
+//                                       the plain state objects the client clones)
+//   globalThis.queueMicrotask           very old WebViews
+// `installCompat(target)` is exported for tests (it patches the given global object instead).
+
+/**
+ * Install the polyfills on `g` (default globalThis). Returns the names that were missing and got installed.
+ * @param {any} [g]
+ * @returns {string[]}
+ */
+export function installCompat(g = globalThis) {
+  const added = [];
+  const def = (obj, name, fn) => {
+    if (!obj || typeof obj[name] === 'function') return;
+    try {
+      Object.defineProperty(obj, name, { value: fn, writable: true, configurable: true, enumerable: false });
+      added.push(name);
+    } catch { /* frozen: leave it */ }
+  };
+  const O = g.Object || Object;
+  def(O, 'hasOwn', function hasOwn(obj, key) {
+    if (obj == null) throw new TypeError('Cannot convert undefined or null to object');
+    return Object.prototype.hasOwnProperty.call(Object(obj), key);
+  });
+  function at(i) {
+    const len = this.length >>> 0;
+    let k = Math.trunc(Number(i)) || 0;
+    if (k < 0) k += len;
+    if (k < 0 || k >= len) return undefined;
+    return typeof this === 'string' || this instanceof String ? String(this).charAt(k) : this[k];
+  }
+  def((g.Array || Array).prototype, 'at', at);
+  def((g.String || String).prototype, 'at', at);
+  const TA = g.Int8Array ? Object.getPrototypeOf(g.Int8Array.prototype) : null;
+  if (TA) def(TA, 'at', at);
+  def((g.Array || Array).prototype, 'findLast', function findLast(fn, thisArg) {
+    for (let i = (this.length >>> 0) - 1; i >= 0; i--) if (fn.call(thisArg, this[i], i, this)) return this[i];
+    return undefined;
+  });
+  def((g.Array || Array).prototype, 'findLastIndex', function findLastIndex(fn, thisArg) {
+    for (let i = (this.length >>> 0) - 1; i >= 0; i--) if (fn.call(thisArg, this[i], i, this)) return i;
+    return -1;
+  });
+  def(g, 'structuredClone', function structuredClone(value) { return cloneValue(value, new Map()); });
+  def(g, 'queueMicrotask', function queueMicrotask(fn) { Promise.resolve().then(fn).catch((err) => setTimeout(() => { throw err; })); });
+  return added;
+}
+
+/** Deep clone of plain data (objects, arrays, Map, Set, Date, RegExp, typed arrays), cycles preserved. */
+function cloneValue(v, seen) {
+  if (v === null || typeof v !== 'object') {
+    if (typeof v === 'function' || typeof v === 'symbol') throw new TypeError('structuredClone: value could not be cloned');
+    return v;
+  }
+  if (seen.has(v)) return seen.get(v);
+  let out;
+  if (v instanceof Date) out = new Date(v.getTime());
+  else if (v instanceof RegExp) out = new RegExp(v.source, v.flags);
+  else if (ArrayBuffer.isView(v)) out = new v.constructor(v);
+  else if (v instanceof ArrayBuffer) out = v.slice(0);
+  else if (v instanceof Map) {
+    out = new Map();
+    seen.set(v, out);
+    for (const [k, x] of v) out.set(cloneValue(k, seen), cloneValue(x, seen));
+    return out;
+  } else if (v instanceof Set) {
+    out = new Set();
+    seen.set(v, out);
+    for (const x of v) out.add(cloneValue(x, seen));
+    return out;
+  } else if (Array.isArray(v)) {
+    out = new Array(v.length);
+    seen.set(v, out);
+    for (let i = 0; i < v.length; i++) out[i] = cloneValue(v[i], seen);
+    return out;
+  } else {
+    out = {};
+    seen.set(v, out);
+    for (const k of Object.keys(v)) out[k] = cloneValue(v[k], seen);
+    return out;
+  }
+  seen.set(v, out);
+  return out;
+}
+
+export const installedPolyfills = installCompat();