feat: add native KDBX scaffolding and in-memory KeePass API

tests/unit/kdbx-crypto.test.ts

@@ -0,0 +1,18 @@
+import { describe, expect, test } from "bun:test";
+import { deriveKey, sha256 } from "../../src/kdbx/crypto";
+
+describe("kdbx crypto helpers", () => {
+	test("sha256 hashes data deterministically", () => {
+		const digest = sha256("abc");
+		expect(Array.from(digest)).toHaveLength(32);
+	});
+
+	test("deriveKey rejects invalid rounds", () => {
+		expect(() => deriveKey("secret", new Uint8Array([1, 2, 3]), 0)).toThrow("Invalid key derivation rounds");
+	});
+
+	test("deriveKey produces a 32-byte key", () => {
+		const key = deriveKey("secret", new Uint8Array([1, 2, 3]), 1000);
+		expect(Array.from(key)).toHaveLength(32);
+	});
+});