i hyperfocused and here is v1

apps/ingest/src/util/verifyGithub.ts

@@ -0,0 +1,19 @@
+import { createHmac, timingSafeEqual } from "node:crypto";
+
+if (!process.env.GITHUB_WEBHOOK_SECRET) {
+  throw new Error("GITHUB_WEBHOOK_SECRET is not defined");
+}
+
+export function verifyGithub(signature: string, body: object): boolean {
+  const verify = createHmac(
+    "sha256",
+    // biome-ignore lint/style/noNonNullAssertion: check is ran before the function
+    process.env.GITHUB_WEBHOOK_SECRET!,
+  )
+    .update(JSON.stringify(body))
+    .digest("hex");
+  return timingSafeEqual(
+    Buffer.from(signature),
+    Buffer.from(`sha256=${verify}`),
+  );
+}