SDL3transition

[JonathSpirit]

This pull request updates the project to use SDL3 and its related libraries instead of SDL2, and makes corresponding changes throughout the build system, dependencies, and example code. It also updates the minimum supported Windows architecture, refines some initialization logic, and improves compatibility with recent CMake versions.

Migration to SDL3 and related libraries:

• Updated all CMake dependency references from SDL2, SDL2_image, and SDL2_mixer to SDL3, SDL3_image, and SDL3_mixer, including version bumps and build flags.
• Changed all CMake target links and runtime DLL copy logic to use SDL3 libraries instead of SDL2. [1] [2] [3] [4]
• Updated all example source files to include SDL3 headers and use updated event and API constants (e.g., SDL_EVENT_QUIT instead of SDL_QUIT). [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]

Build system and dependency improvements:

• Updated CMake minimum version for dependencies and CI to 4.4.x, and upgraded actions-setup-cmake to v2.2.0 in all workflows. [1] [2] [3] [4]
• Expanded the list of SDL dependencies installed in CI workflows for better coverage and compatibility. [1] [2]
• Removed 32-bit Windows build from the matrix, reflecting the new supported architectures.
• Updated README to clarify that only UCRT 64-bit Windows is supported, and 32-bit is not tested on Windows.

API and code improvements:

• Migrated from fge::SoundBuffer to the new fge::Audio class in the Creature example, updating usage accordingly. [1] [2] [3]
• Improved resource manager initialization in examples to check for errors and print messages if initialization fails. [1] [2]
• Fixed event handling logic in examples to use updated SDL3 event constants and structure members. [1] [2]

Other changes:

• Added missing source file C_audio.cpp to the build.
• Removed unused workaround for SDL2main in CMake.

These changes collectively modernize the codebase, improve build reliability, and ensure compatibility with the current SDL and CMake ecosystems.