Promotes the inline curl-popen pattern duplicated across apps/services_monitor,
dag_engine_ui, data_factory into two reusable functions in cpp/functions/core/:
- http_request_cpp_core: generic HTTP client (GET/POST/PUT/DELETE/PATCH) via
cURL CLI through popen. Portable Linux/WSL/MinGW (no link-time libcurl).
Supports custom headers, raw body, Bearer/Basic auth shortcuts, timeout,
optional TLS verify skip. Returns status/body/headers/error/duration_ms.
- http_get_json_cpp_core: convenience wrapper over http_request — GET <url>,
expect 2xx, parse body as nlohmann::json. Throws std::runtime_error on
transport / non-2xx / parse failure.
Vendors nlohmann/json v3.11.3 single header at cpp/vendor/nlohmann/json.hpp
(MIT). No CMake target needed — header-only; consumers add
cpp/vendor/ to include path.
