Add Windows build to binary release workflow

- Add build-windows job to build clang and clangd for Windows x86_64
- Uses PowerShell syntax for cmake configuration
- Produces clang-nullsafe-windows-x86_64.tar.gz with clang.exe and clangd.exe
- Now building for all three major platforms: Linux, macOS, and Windows

Author: cs01

.github/workflows/build-clang.yml

@@ -159,3 +159,73 @@ jobs:
             See the [README](https://github.com/cs01/llvm-project/blob/null-safe-c-dev/README.md) for usage instructions.
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  build-windows:
+    runs-on: windows-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: |
+          choco install ninja cmake
+
+      - name: Configure build
+        run: |
+          mkdir build
+          cd build
+          cmake -G Ninja `
+            -DCMAKE_BUILD_TYPE=Release `
+            -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" `
+            -DLLVM_TARGETS_TO_BUILD="X86" `
+            -DLLVM_ENABLE_ASSERTIONS=OFF `
+            -DCMAKE_INSTALL_PREFIX=../install `
+            ../llvm
+
+      - name: Build Clang and clangd
+        run: |
+          cd build
+          ninja clang clangd
+
+      - name: Install Clang and clangd
+        run: |
+          cd build
+          ninja install-clang
+          ninja install-clang-headers
+          ninja install-clangd
+
+      - name: Package binaries
+        run: |
+          cd install
+          tar -czf clang-nullsafe-windows-x86_64.tar.gz bin/ lib/clang/
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: clang-nullsafe-windows-x86_64
+          path: install/clang-nullsafe-windows-x86_64.tar.gz
+
+      - name: Create Release
+        uses: softprops/action-gh-release@v1
+        with:
+          files: install/clang-nullsafe-windows-x86_64.tar.gz
+          body: |
+            ## Null-Safe Clang Binary Release (Windows)
+
+            This release contains the Null-Safe Clang compiler and clangd language server for Windows x86_64.
+
+            ### What's included:
+            - `clang.exe` - The Null-Safe C compiler
+            - `clangd.exe` - Language server for IDE integration (VSCode, vim, etc.)
+
+            ### Installation:
+            ```bash
+            tar -xzf clang-nullsafe-windows-x86_64.tar.gz
+            # Add bin/ directory to your PATH
+            clang --version
+            ```
+
+            See the [README](https://github.com/cs01/llvm-project/blob/null-safe-c-dev/README.md) for usage instructions.
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}