feat(rednote): add isolated persistent browser H5 entry

h5/lib/provider-gate.js

@@ -0,0 +1,17 @@
+'use strict';
+// Rednote-only admission control. Includes JSON consumption in the critical section.
+module.exports = function providerGate(fetchImpl, maxPending = 4) {
+  let tail = Promise.resolve(), pending = 0;
+  return function (...args) {
+    if (pending >= maxPending) return Promise.reject(Error('Detection queue is full'));
+    pending++;
+    const result = tail.then(async () => {
+      args[1]?.signal?.throwIfAborted();
+      const response = await fetchImpl(...args);
+      const data = await response.json();
+      return { ok: response.ok, status: response.status, json: async () => data };
+    });
+    tail = result.catch(() => {}).finally(() => { pending--; });
+    return result;
+  };
+};