Remove PNG and ZLIB support from the project

- Eliminated all references to PNG and ZLIB dependencies in CMake configuration and project files.
- Updated documentation to reflect the removal of PNG support and related functionalities.
- Adjusted build scripts and source files to remove unused code related to PNG handling, ensuring a cleaner codebase.

cmake/sdl2.cmake

@@ -26,35 +26,4 @@ else()
   endif()
 endif()
 
-# libpng and ZLIB dependencies  
-if(WIN32)
-  # Windows builds with vcpkg (OpenGL/GLEW removed to avoid MSYS2 issues)
-  if(NOT YAZE_MINIMAL_BUILD)
-    find_package(ZLIB REQUIRED)
-    find_package(PNG REQUIRED)
-  else()
-    # For CI/minimal builds, try to find but don't require
-    find_package(ZLIB QUIET)
-    find_package(PNG QUIET)
-    if(NOT ZLIB_FOUND OR NOT PNG_FOUND)
-      message(STATUS "PNG/ZLIB not found in minimal build, some features may be disabled")
-      set(PNG_FOUND FALSE)
-      set(PNG_LIBRARIES "")
-      set(PNG_INCLUDE_DIRS "")
-    endif()
-  endif()
-elseif(YAZE_MINIMAL_BUILD)
-  # For CI builds on other platforms, try to find but don't require
-  find_package(ZLIB QUIET)
-  find_package(PNG QUIET)
-  if(NOT ZLIB_FOUND OR NOT PNG_FOUND)
-    message(STATUS "PNG/ZLIB not found in minimal build, some features may be disabled")
-    set(PNG_FOUND FALSE)
-    set(PNG_LIBRARIES "")
-    set(PNG_INCLUDE_DIRS "")
-  endif()
-else()
-  # Regular builds require these dependencies
-  find_package(ZLIB REQUIRED)
-  find_package(PNG REQUIRED)
-endif()
+# PNG and ZLIB dependencies removed