Fix Windows build errors: config_parser.h, poll(), localtime()

- Replace sys/socket.h with platform_compat.h in config_parser.h
- Add #include <poll.h> for Windows in platform_compat.h
- Fix localtime() type mismatch: cast tv.tv_sec to time_t
- All 22 tests pass on Linux

lib/platform_compat.h

@@ -103,6 +103,9 @@
     
     // nanosleep already defined in pthread_time.h on MSYS2
     
+    // poll is in ws2tcpip.h or poll.h on MSYS2
+    #include <poll.h>
+    
 #else
     // POSIX - include standard headers
     #include <sys/time.h>