Upstream fixes present:
- libffi.gyp: correct preprocess_asm.cmd path for Windows (node-ffi-napi#293, node-ffi-napi#265)
- src/ffi.cc: remove NAPI_EXPERIMENTAL define (node-ffi-napi#283)
- node-gyp-build bumped to ^4.8.2, prebuildify to ^6.0.1 (node-ffi-napi#283)

* Bump version to 4.0.5

Upstream fixes present:
- libffi.gyp: correct preprocess_asm.cmd path for Windows (node-ffi-napi#293, node-ffi-napi#265)
- src/ffi.cc: remove NAPI_EXPERIMENTAL define (node-ffi-napi#283)
- node-gyp-build bumped to ^4.8.2, prebuildify to ^6.0.1 (node-ffi-napi#283)
- Supported on node 22 (Linux/Mac/Windows/Mingw) node-ffi-napi#281 node-ffi-napi#270


* Add MinGW (MSYS2 MINGW64) build and test job

Uses MSYS2's own Node.js package so os.type() returns MINGW64_NT-*,
which activates the MinGW code path in libffi.gyp (GCC compiles .S
files directly instead of the MSVC preprocess_asm.cmd route).

* Improve MSYS2 detection

* Use MSYSTEM_PREFIX to detect MSYS2 toolchain instead of MSYSTEM

* Skip uv_fs_open symbol check on MinGW/MSYS2 Windows builds

On MSYS2 MinGW nodes, libuv is not necessarily re-exported from the
node binary, so GetProcAddress("uv_fs_open") returns error 127. The
test still verifies that Library(null, {}) succeeds on MinGW; only the
MSVC-specific symbol export assumption is skipped.