feat(ci): add driver input to setup-buildx action (#941)

Signed-off-by: Jonas Toelke <jtoelke@nvidia.com>

Author: jtoelke2

.github/actions/setup-buildx/action.yml

@@ -1,15 +1,22 @@
 name: Setup Docker Buildx
 description: >
-  Create a multi-arch Docker Buildx builder using remote BuildKit nodes.
-  The builder is automatically removed when the job finishes (cleanup is
-  enabled by default in docker/setup-buildx-action).
+  Create a Docker Buildx builder. Two modes:
+    * driver=remote (default) — multi-arch builder against in-cluster BuildKit
+      pods. Requires EKS connectivity. Behaviour unchanged from prior versions.
+    * driver=local — single-node buildx on the local docker-container driver.
+      Pair with cache-to/cache-from=type=gha on build steps for persistence.
+      Works on nv-gha-runners; no EKS needed.
+  Cleanup is automatic when the job finishes (docker/setup-buildx-action default).
 
 inputs:
+  driver:
+    description: "buildx driver: 'remote' or 'local'"
+    default: remote
   amd64-endpoint:
-    description: BuildKit endpoint for linux/amd64
+    description: BuildKit endpoint for linux/amd64 (remote driver only)
     default: tcp://buildkit-amd64.buildkit:1234
   arm64-endpoint:
-    description: BuildKit endpoint for linux/arm64
+    description: BuildKit endpoint for linux/arm64 (remote driver only)
     default: tcp://buildkit-arm64.buildkit:1234
   name:
     description: Builder instance name
@@ -18,7 +25,8 @@ inputs:
 runs:
   using: composite
   steps:
-    - name: Set up Docker Buildx
+    - name: Set up Docker Buildx (remote)
+      if: inputs.driver == 'remote'
       uses: docker/setup-buildx-action@v3
       with:
         name: ${{ inputs.name }}
@@ -28,3 +36,11 @@ runs:
         append: |
           - endpoint: ${{ inputs.arm64-endpoint }}
             platforms: linux/arm64
+
+    - name: Set up Docker Buildx (local)
+      if: inputs.driver == 'local'
+      uses: docker/setup-buildx-action@v3
+      with:
+        name: ${{ inputs.name }}
+        driver: docker-container
+        platforms: linux/amd64,linux/arm64