chore(app): set Windows app entry point to WinMain

src/app/CMakeLists.txt

@@ -1,7 +1,7 @@
 if(WHOA_SYSTEM_WIN)
     file(GLOB PRIVATE_SOURCES "win/*.cpp")
 
-    add_executable(Whoa ${PRIVATE_SOURCES})
+    add_executable(Whoa WIN32 ${PRIVATE_SOURCES})
 
     target_link_libraries(Whoa
         PRIVATE

src/app/win/Whoa.cpp

@@ -1,6 +1,6 @@
 #include "client/Client.hpp"
 
-int main(int argc, char* argv[]) {
+int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd) {
     // TODO
 
     CommonMain();