Enhance CMake configuration for PNG support and introduce vcpkg.json

- Updated CMakeLists.txt to conditionally enable PNG support based on the presence of the PNG library, improving compatibility for minimal builds.
- Added vcpkg.json to manage project dependencies, including zlib, libpng, sdl2, and abseil, streamlining package management.
- Modified CI workflow in ci.yml to simplify CMake configuration commands for better readability.
- Enhanced CMake scripts to ensure proper handling of dependencies in both minimal and regular builds, improving build reliability.

src/app/core/project.cc

@@ -1,6 +1,7 @@
 #include "project.h"
 
 #include <fstream>
+#include <sstream>
 #include <string>
 
 #include "app/gui/icons.h"