chore: sign Windows binary with DigiCert EV certificate

Add a sign-windows job to the release workflow that signs ant-node.exe
using DigiCert SSM before the post-quantum signing step. The signed
binary is repackaged into the release archive. Mirrors the approach
used in ant-client.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jacderida

.github/workflows/release.yml

@@ -187,17 +187,137 @@ jobs:
           path: ant-node-cli-${{ matrix.friendly_name }}.${{ matrix.archive }}
           retention-days: 1
 
+  sign-windows:
+    name: Sign Windows Binary
+    runs-on: windows-latest
+    needs: [build]
+    env:
+      SM_HOST: ${{ secrets.SM_HOST }}
+      SM_API_KEY: ${{ secrets.SM_API_KEY }}
+      SM_CLIENT_CERT_PASSWORD: ${{ secrets.SM_CLIENT_CERT_PASSWORD }}
+      SM_KEYPAIR_ALIAS: ${{ secrets.SM_KEYPAIR_ALIAS }}
+      SM_LOG_LEVEL: info
+      SM_LOG_FILE: ${{ github.workspace }}\smctl-signing.log
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/download-artifact@v4
+        with:
+          name: cli-windows-x64
+          path: artifacts/
+
+      - name: Extract binary for signing
+        shell: bash
+        run: |
+          cd artifacts
+          7z x *.zip
+          if [ ! -f "ant-node.exe" ]; then
+            echo "::error::ant-node.exe not found after extraction"
+            ls -R
+            exit 1
+          fi
+
+      - name: Create client certificate file
+        id: prepare_cert
+        shell: pwsh
+        run: |
+          $raw = @'
+          ${{ secrets.SM_CLIENT_CERT_B64 }}
+          '@
+
+          $clean = ($raw -replace '\s','')
+
+          if ([string]::IsNullOrWhiteSpace($clean)) {
+            Write-Error "SM_CLIENT_CERT_B64 is empty after normalization."
+            exit 1
+          }
+
+          try {
+            [Convert]::FromBase64String($clean) | Out-Null
+          } catch {
+            Write-Error "SM_CLIENT_CERT_B64 is not valid Base64."
+            exit 1
+          }
+
+          Write-Host "::add-mask::$clean"
+          "sm_client_cert_b64=$clean" | Out-File -FilePath $env:GITHUB_OUTPUT -Append
+
+      - name: Setup DigiCert SSM tools
+        uses: digicert/ssm-code-signing@v1.2.1
+        with:
+          sm_host: ${{ secrets.SM_HOST }}
+          sm_api_key: ${{ secrets.SM_API_KEY }}
+          sm_client_cert_b64: ${{ steps.prepare_cert.outputs.sm_client_cert_b64 }}
+          sm_client_cert_password: ${{ secrets.SM_CLIENT_CERT_PASSWORD }}
+
+      - name: Verify smctl installation
+        shell: pwsh
+        run: |
+          smctl -v
+          smctl healthcheck
+
+      - name: Sign ant-node.exe
+        shell: pwsh
+        run: |
+          $file = "artifacts\ant-node.exe"
+          $result = & smctl sign --keypair-alias "$env:SM_KEYPAIR_ALIAS" --input "$file" 2>&1
+          if ($LASTEXITCODE -ne 0) {
+            Write-Error "Signing failed: $result"
+            exit 1
+          }
+          Write-Host "Successfully signed ant-node.exe"
+
+      - name: Verify signature
+        shell: pwsh
+        run: |
+          $sig = Get-AuthenticodeSignature "artifacts\ant-node.exe"
+          Write-Host "Status: $($sig.Status)"
+          Write-Host "Signer: $($sig.SignerCertificate.Subject)"
+          if ($sig.Status -ne "Valid") {
+            Write-Error "Signature validation failed"
+            exit 1
+          }
+
+      - name: Repackage signed archive
+        shell: bash
+        run: |
+          staging="ant-node-cli-windows-x64"
+          rm -rf "$staging"
+          mkdir "$staging"
+          cp artifacts/ant-node.exe "$staging/"
+          cp config/bootstrap_peers.toml "$staging/"
+          (cd "$staging" && 7z a "../${staging}.zip" ./*)
+
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: signed-windows-x64
+          path: ant-node-cli-windows-x64.zip
+          retention-days: 1
+
   sign:
     name: Sign Releases
-    needs: [build]
+    needs: [build, sign-windows]
     runs-on: ubuntu-latest
     steps:
-      - name: Download all artifacts
+      - name: Download build artifacts (excluding signed)
         uses: actions/download-artifact@v4
         with:
+          pattern: cli-*
           path: artifacts
           merge-multiple: true
 
+      - name: Download signed Windows artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: signed-windows-x64
+          path: artifacts-signed-win
+
+      - name: Replace Windows archive with signed version
+        run: |
+          rm -f artifacts/ant-node-cli-windows-x64.zip
+          cp artifacts-signed-win/*.zip artifacts/
+
       - name: List artifacts
         run: ls -la artifacts/
 
@@ -322,6 +442,10 @@ jobs:
             ant-keygen verify --key release-signing-key.pub --input <file> --signature <file>.sig
             ```
 
+            The Windows binary (`ant-node.exe`) is additionally signed with a DigiCert EV
+            code-signing certificate. Windows will verify this signature automatically on
+            download and execution.
+
             SHA256 checksums provided in `SHA256SUMS.txt`.
 
             ### Auto-Upgrade