update build system to work on modern tools, add macOS Apple Silicon

[jbsohn]

Changes made to support modern hardware, compilers, and scripting environments across Windows, macOS, and Linux.

Apple Silicon Support (macOS arm64)

• Added the new macosx_arm64 build target.
• The emulator now runs natively on Apple Silicon Macs without requiring Rosetta 2 translation.
• Updated SDL2 linking logic to support both static and shared library configurations on macOS.

3rdparty

• Update to the latest SDL2

Universal Python 3 Migration

• Compatibility: All internal build scripts have been updated to be fully compatible with Python 3.11+.
• Fixes:
  • Replaced deprecated tostring() method calls with tobytes().
  • Removed the unsupported rU (Universal Newlines) file opening mode.
  • Updated msgfmt.py, verinfo.py, m6502make.py, and png.py.

Modern GCC 15 / C++ Readiness

• Header Cleanup: Added explicit #include <string> to files like effect.h where modern GCC no longer provides them transitively.
• Template Disambiguation: Resolved template overload ambiguities in the sol2 Lua wrapper to satisfy the strict requirements of GCC 15.

4. Windows (MSYS2/UCRT64) Robustness

• GENie Fix: Patched the genie project generator to prevent path concatenation errors (mangled paths) when archiving large libraries on Windows.
• Git Housekeeping: Updated .gitignore to properly hide Windows-specific artifacts (.exe, ui.ini) and generated folders (cfg/, history/).

Build Information

• Windows Build: MSYS2 with the UCRT64 toolchain.
• Default Renderer: Set to OpenGL/GLSL for non-macOS systems to improve out-of-the-box performance.

Other Information

• I have verified basic functionality across Linux, Windows, and macOS. Given the variety of possible configurations, I would appreciate community validation to catch any edge cases.
• Despite the large diff, the majority of this PR is a dependency refresh within 3rdparty. The actual emulator logic changes are minimal, specifically targeting compatibility with GCC 15 and Python 3.11+.
• I've intentionally kept YM2149 on-cart support in a separate branch (ym2149) to ensure this PR remains focused strictly on updates to work with modern tools.