feat: switch email delivery from Resend to SMTP with libcurl integration

CMakeLists.txt

@@ -9,6 +9,7 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
 find_package(Python3 COMPONENTS Interpreter REQUIRED)
 find_package(OpenSSL REQUIRED)
+find_package(CURL REQUIRED)
 
 option(USE_SYSTEM_DROGON "Use an installed Drogon package instead of CPM" OFF)
 
@@ -72,6 +73,7 @@ target_include_directories(${PROJECT_NAME}
 target_link_libraries(${PROJECT_NAME}
     PRIVATE
         Drogon::Drogon
+        CURL::libcurl
         OpenSSL::Crypto
 )