feat: 完成源晶权限与经验系统并优化 me/admin 交互

backend/tests/auth_service_test.cc

@@ -20,4 +20,14 @@ TEST_CASE("auth register/login/verify") {
   const auto r2 = auth.Login("alice", "password123");
   REQUIRE(r2.user_id == r.user_id);
   REQUIRE(r2.token != r.token);
+
+  const auto verified = auth.VerifyCredentials("alice", "password123");
+  REQUIRE(verified.has_value());
+  REQUIRE(verified.value() == r.user_id);
+
+  const auto wrong_password = auth.VerifyCredentials("alice", "wrongpass");
+  REQUIRE_FALSE(wrong_password.has_value());
+
+  const auto wrong_user = auth.VerifyCredentials("missing_user", "password123");
+  REQUIRE_FALSE(wrong_user.has_value());
 }