[windows] add experimental CI support

Manual trigger only, for testing `try-windows` branch.

For now, just build `libtom{crypt,math}` dependencies on Windows; later, perhaps hook them up to Swift. The latter steps would fail and that's expected.

.github/workflows/x-win.yml

@@ -0,0 +1,109 @@
+name: Experiment-Windows
+on:
+  workflow_dispatch: # manually-triggered runs
+
+permissions:
+  # only allowed to read source code (ref. https://docs.github.com/en/actions/using-jobs/assigning-permissions-to-jobs)
+  contents: read
+
+concurrency:
+  # cancel pending runs when a PR gets updated
+  group: "${{ github.head_ref || github.run_id }}-${{ github.actor }}"
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: "X-Win - ${{ matrix.name }}"
+
+    strategy:
+      matrix:
+        include:
+          #TODO(later)
+          #- name: "Ubuntu ARM64"
+          #  os:
+          #    - ARM64
+          #    - linux
+          #    - Ubuntu
+          #  env:
+          #    OS: "linux"
+          #    NUGET_RID: "linux-arm64"
+
+          #- name: "Ubuntu x64"
+          #  os:
+          #    - X64
+          #    - linux
+          #    - Ubuntu
+          #  env:
+          #    OS: "linux"
+          #    NUGET_RID: "linux-x64"
+          #    NUGET_PACK_DOTNET_LIB: "1"
+
+          #- name: "MacOS ARM64"
+          #  os: macos-14
+          #  env:
+          #    OS: "apple"
+          #    NUGET_RID: "osx"
+
+          - name: "Windows x64"
+            os: windows-latest
+            env:
+              OS: "windows"
+              NUGET_RID: "win-x64"
+
+    runs-on: "${{ matrix.os }}"
+
+    defaults:
+      run:
+        shell: "${{ matrix.env.OS == 'windows' && 'pwsh' || 'bash' }}"
+
+    env:
+      DOTNET_NOLOGO: 1
+      DOTNET_CLI_TELEMETRY_OPTOUT: 1
+      DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 1
+      VCPKG_DISABLE_METRICS: 1
+      NUGET_BASE_VERSION: "0.0"
+      SCRIPT_EXT: "${{ matrix.env.OS == 'windows' && 'ps1' || 'sh' }}"
+      ROYALVNC_BUILD_DEBUG: 0
+      SWIFT_VERSION: "6.0"
+
+    steps:
+    - name: checkout
+      uses: actions/checkout@v4
+
+    # setup build environment
+
+    - name: setup environment (Apple)
+      if: "success() && matrix.env.OS == 'apple'"
+      run: |
+        sudo xcode-select --switch /Applications/Xcode_16.0.app
+
+    - name: setup VC++ environment (Windows)
+      if: "success() && matrix.env.OS == 'windows'"
+      uses: compnerd/gha-setup-vsdevenv@v6
+
+    - name: setup Swift (Windows)
+      if: "success() && matrix.env.OS == 'windows'"
+      uses: compnerd/[email protected]
+      with:
+        branch: "swift-${{ env.SWIFT_VERSION }}-release"
+        tag: "${{ env.SWIFT_VERSION }}-RELEASE"
+
+    # setup dependencies
+
+    - name: dependencies
+      if: "success() && matrix.env.OS == 'windows'"
+      run: |
+        Scripts/windows/dependencies.ps1
+
+    # build RoyalVNCKit
+
+    - name: build RoyalVNCKit
+      run: |
+        swift package clean --configuration "release"
+        swift build --configuration "release"
+
+    # .NET bindings and NuGet package artifacts
+
+    - name: build .NET bindings
+      run: |
+        dotnet build "Bindings/dotnet/RoyalApps.RoyalVNCKit.sln" -c Release