fix(voice-call): harden inbound policy

extensions/voice-call/src/allowlist.ts

@@ -0,0 +1,19 @@
+export function normalizePhoneNumber(input?: string): string {
+  if (!input) {
+    return "";
+  }
+  return input.replace(/\D/g, "");
+}
+
+export function isAllowlistedCaller(
+  normalizedFrom: string,
+  allowFrom: string[] | undefined,
+): boolean {
+  if (!normalizedFrom) {
+    return false;
+  }
+  return (allowFrom ?? []).some((num) => {
+    const normalizedAllow = normalizePhoneNumber(num);
+    return normalizedAllow !== "" && normalizedAllow === normalizedFrom;
+  });
+}