windows cloud build?

.github/workflows/build-all.yml

@@ -12,3 +12,6 @@ jobs:
 
   build-macos:
     uses: ./.github/workflows/build-macos.yml
+
+  build-windows:
+    uses: ./.github/workflows/build-windows.yml

.github/workflows/build-linux.yml

@@ -12,7 +12,7 @@ defaults:
     shell: bash
 
 jobs:
-  build:
+  build-linux:
     runs-on: ubuntu-22.04
     # We prefer slightly older Ubuntu so we get binaries that work on
     # all more recent versions.

.github/workflows/build-macos.yml

@@ -5,7 +5,7 @@ on:
   workflow_call:
 
 jobs:
-  build:
+  build-macos:
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@master

.github/workflows/build-windows.yml

@@ -0,0 +1,60 @@
+name: Build F* (Windows)
+
+# Build F* on Windows
+
+on:
+  workflow_call:
+  workflow_dispatch:
+  push:
+
+defaults:
+  run:
+    shell:
+      bash
+      # ^ avoid powershell!
+
+jobs:
+  build-windows:
+    # NOTE! Unlike our other builds, this requires a self-hosted
+    # runner (for now?)
+    runs-on: [self-hosted, Windows, X64, opam-2-3]
+
+    steps:
+      - uses: actions/checkout@master
+        with:
+          path: FStar
+
+      # self-hosted runner already set up
+      # - uses: ocaml/setup-ocaml@v3
+      #   with:
+      #     ocaml-compiler: 4.14.2
+      # - name: Prepare
+      #   shell: powershell # somehow in bash we fail to build ocamlfind?
+      #   run: |
+      #     ./FStar/.scripts/get_fstar_z3.sh $HOME/bin
+      #     echo "PATH=$HOME/bin:$PATH" >> $GITHUB_ENV
+      #     opam install --deps-only FStar\fstar.opam
+
+      - 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 FStar/version.txt)" >> $GITHUB_ENV
+          fi
+
+      - name: Build package
+        shell: C:\cygwin64\bin\bash.exe --login '{0}'
+        working-directory: FStar
+        run: |
+          eval $(opam env)
+          export CC=x86_64-w64-mingw32-gcc.exe
+          make -skj$(nproc) package FSTAR_TAG=-Windows_NT-x86_64 V=1
+
+      - uses: actions/upload-artifact@v4
+        with:
+          path: FStar\fstar-Windows_NT-x86_64.tar.gz
+          name: fstar-Windows_NT-x86_64.tar.gz