Fix deserialize_ResponseResult

[gophergogo]

In MCP example client, having output:

  test.log:  [FAIL] Resource: config://server/settings - Not found
  test.log:  [FAIL] Resource: log://server/events - Not found
  test.log:  [FAIL] Resource: metrics://server/stats - Not found

// Test counter for tracking pass/fail
  struct TestResults {
    int passed = 0;
    int failed = 0;

    void pass(const std::string& test_name) {
      passed++;
      std::cerr << "  [PASS] " << test_name << std::endl;
    }

    void fail(const std::string& test_name, const std::string& reason = "") {
      failed++;
      std::cerr << "  [FAIL] " << test_name;
      if (!reason.empty()) {
        std::cerr << " - " << reason;
      }
      std::cerr << std::endl;
    }

    void summary() {
      std::cerr << "\n========================================" << std::endl;
      std::cerr << "TEST SUMMARY: " << passed << " passed, " << failed
                << " failed" << std::endl;
      std::cerr << "========================================" << std::endl;
    }
  };

PR

#151