MEM-010: CURL unchecked alloc + handle/slist leaks (abc/CURL.c)

CURLGet/CURLPost dereference calloc() and curl_easy_init() results without a NULL check (NULL write/deref under memory pressure or handle-init failure), the curl_multi_add_handle error path frees the request buffers but never curl_easy_cleanups the easy handle, and every POST with a content type leaks its curl_slist headers (libcurl does not take ownership). The goal is to null-check the allocations and free the handle and slist on the right paths.

Issues

One null-deref plus two resource leaks in the request lifecycle.

Blockers

None.

Planned

Check allocations; release handle and slist exactly once at completion.