Fix Windows header and build style inconsistencies

[linmajia]

Updates Windows-specific code style and build configuration:

• Normalize Windows SDK header casing to lowercase, e.g. <windows.h>, <winsock2.h>, <tlhelp32.h>.
• Ensure Winsock headers are included before <windows.h>.
• Move Windows system library dependencies from source pragmas into CMake via DSN_SYSTEM_LIBS.
• Add ws2_32 and psapi for Windows builds.
• Fix the ntohl/htonl helper type check in ports.h to use u_long.
• Normalize Windows conditional include ordering in main.cpp and service_api_c.cpp.