This commit fixes multiple compilation errors introduced by the refactoring:
1. Added missing http_client_conn_free() helper function
2. Fixed cookie_jar reference (cookie_jar->count to client->cookie_jar.count)
3. Restored missing HTTP_ClientConn fields: handle, client, and url
4. Fixed undefined 'conn' variable in http_client_get_builder (changed to 'i')
5. Fixed incorrect field reference (entry.domain.len to domain.len)
6. Added missing closing parenthesis in should_send_cookie
7. Removed duplicate 'path' variable declaration
8. Fixed cookie jar access to use builder.client instead of conn->client
9. Fixed byte_queue_write calls to use .ptr and .len instead of HTTP_String structs
10. Fixed missing -> operators in url_to_connect_target
11. Fixed undefined 'url' variable by using conn->url
12. Fixed headers[i].value to set_cookie.value in save_one_cookie
13. Fixed typo: antry to entry
14. Fixed save_one_cookie parameter type (headers[i] instead of headers[i].value)
15. Fixed print_bytes calls to create HTTP_String structs
16. Added logic to store socket handle when connection is established
17. Updated http_client_get_builder signature to return HTTP_RequestBuilder
18. Updated simple_client.c example to match new API