Make: Build JavaScript Windows x64 prebuilds (#774)

The `build_javascript` job exported `CC=gcc`/`CXX=g++` for every OS. On
Windows `node-gyp` ignores both and builds with MSVC, but NumKong's ISA
probe reads the compiler from `$CC` while still emitting MSVC flag
syntax, so it shells out to `gcc /c /arch:AVX2 ... /nologo`. Every probe
fails, the failures are swallowed, and `nk_probes.h` lands with all 39
`NK_TARGET_*` set to zero.

The addon still builds and passes the test suite -- dynamic dispatch just
has no kernels to choose from -- so the result is a scalar-only binary
shipped to every Windows npm user. Scope the variables to the Linux step
and let the probe fall back to `cl.exe`, which enables Haswell and
Skylake.

Co-authored-by: Evgeniy Peshkov <2716874+GraDea@users.noreply.github.com>
Co-authored-by: Ash Vardanian <1983160+ashvardanian@users.noreply.github.com>

Author: GraDea

.github/workflows/release.yml

@@ -813,19 +813,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        arch: [x64, x86]
-        # Windows pre-build is not working
-        # - windows-latest
-        os: [macos-14, ubuntu-24.04]
-        exclude:
-          - arch: x86
-            os: macos-14
-          - arch: x86
-            os: ubuntu-24.04
+        arch: [x64]
+        os: [macos-14, ubuntu-24.04, windows-2022]
     runs-on: ${{ matrix.os }}
-    env:
-      CC: gcc
-      CXX: g++
 
     steps:
       - name: Checkout the latest code
@@ -852,7 +842,16 @@ jobs:
         run: |
           npm install --ignore-scripts
       - run: npm run prebuild-single
-        if: matrix.os != 'macos-14'
+        env:
+          CC: gcc
+          CXX: g++
+        if: matrix.os == 'ubuntu-24.04'
+        # Leave CC/CXX unset on Windows. node-gyp builds with MSVC regardless,
+        # but NumKong's ISA probe takes the compiler from $CC while still
+        # passing MSVC flag syntax, so a `gcc` here fails every probe and
+        # silently yields a scalar-only binary with no SIMD kernels.
+      - run: npm run prebuild-single
+        if: matrix.os == 'windows-2022'
       - run: npm run prebuild-darwin-x64+arm64
         env:
           CC: clang