Change to SHA256 hashing

frontend/sync-client/src/utils/hash.test.ts

@@ -0,0 +1,7 @@
+import assert from "node:assert";
+import { test } from "node:test";
+import { EMPTY_HASH, hash } from "./hash";
+
+void test("EMPTY_HASH is the SHA-256 hash of empty content", async () => {
+    assert.strictEqual(await hash(new Uint8Array()), EMPTY_HASH);
+});