fix(ci): use GHCR_ACTOR and GHCR_TOKEN vars for registry login

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: guzman109

.github/workflows/build.yaml

@@ -1,3 +1,4 @@
+
 name: build
 
 on:
@@ -96,8 +97,8 @@ jobs:
         uses: docker/login-action@v3
         with:
           registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
+          username: ${{ vars.GHCR_ACTOR }}
+          password: ${{ secrets.GHCR_TOKEN }}
 
       - name: Build and push runtime image
         uses: docker/build-push-action@v6
@@ -128,3 +129,4 @@ jobs:
         uses: softprops/action-gh-release@v2
         with:
           files: icicle-insights-linux-amd64.tar.gz
+