Restoring self-hosted windows build

.github/workflows/build-windows-selfhosted.yml

@@ -0,0 +1,43 @@
+name: Build F* (Windows, self-hosted)
+
+on:
+  workflow_call:
+  workflow_dispatch:
+  push:
+
+jobs:
+  build-windows:
+    runs-on: [self-hosted, Windows, X64, opam-2-3]
+    # NOTE: no setup, the self-hosted runner already has all that is needed.
+    steps:
+    - name: Check out repo
+      uses: actions/checkout@v4
+
+    - name: Set version
+      shell: C:\cygwin64\bin\bash.exe --login '{0}'
+      run: |
+        # Setting FSTAR_VERSION for nightly and release builds. If unset,
+        # we use $(version.txt)~dev. Setting it avoids the ~dev.
+        if [[ "${{github.workflow_ref}}" =~ "nightly.yml" ]]; then echo FSTAR_VERSION="nightly-$(date -I)" >> $GITHUB_ENV; elif [[ "${{github.workflow_ref}}" =~ "release.yml" ]]; then echo FSTAR_VERSION="$(cat version.txt)" >> $GITHUB_ENV; echo FSTAR_RELEASE=1 >> $GITHUB_ENV; fi
+
+    - name: Build a package
+      shell: C:\cygwin64\bin\bash.exe --login '{0}'
+      run: |
+        eval $(opam env)
+        export CC=x86_64-w64-mingw32-gcc.exe
+        make -j$(nproc) package
+
+    - name: Test the package
+      shell: C:\cygwin64\bin\bash.exe --login '{0}'
+      run: |
+        eval $(opam env)
+        export CC=x86_64-w64-mingw32-gcc.exe
+        export CI_THREADS=$(nproc)
+        .scripts/test_package.sh
+        echo "There is a CR at the end of this line"
+
+    - name: Upload artifact
+      uses: actions/upload-artifact@v4
+      with:
+        path: fstar-*.zip
+        name: package-win

.github/workflows/ci.yml

@@ -2,6 +2,8 @@ name: CI
 
 on:
   push:
+    branches-ignore:
+    - _**
   pull_request:
   workflow_dispatch:
   merge_group: