fix: buildkitd network + TCP listener for remote driver

Two bugs made the first CI run fail with 'waiting for connection:
context deadline exceeded':

1. Container started without --network landed on default bridge,
   while job containers run on git_default -> name unresolvable,
   bridge IP unreachable cross-network.

2. moby/buildkit default entrypoint only listens on a unix socket.
   driver: remote needs TCP. Added --addr tcp://0.0.0.0:8375 and
   changed endpoint from docker-container://name (only valid for
   the docker-container driver) to tcp://name:8375.

Both verified on the oracle host: buildx remote driver connects,
Status running, platforms linux/arm64,v7,v6.

action.yml

@@ -21,6 +21,14 @@ inputs:
     description: 'Stop the buildkitd container after the job (idle cleanup; container restarts on demand on the next run)'
     required: false
     default: 'true'
+  network:
+    description: 'Docker network for the buildkitd container — MUST match the network the job containers run on, otherwise the name is unresolvable'
+    required: false
+    default: 'git_default'
+  port:
+    description: 'TCP port buildkitd listens on'
+    required: false
+    default: '8375'
 
 runs:
   using: 'composite'
@@ -30,16 +38,17 @@ runs:
       run: |
         docker ps -a --format '{{.Names}}' | grep -qx '${{ inputs.container_name }}' || \
         docker run -d --name ${{ inputs.container_name }} --privileged \
+          --network ${{ inputs.network }} \
           --restart unless-stopped \
           --label com.centurylinklabs.watchtower.monitor-only=${{ inputs.monitor_only }} \
           --label dockhand.notify=${{ inputs.dockhand_notify }} \
-          ${{ inputs.image }}
+          ${{ inputs.image }} --addr tcp://0.0.0.0:${{ inputs.port }}
 
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v4
       with:
         driver: remote
-        endpoint: docker-container://${{ inputs.container_name }}
+        endpoint: tcp://${{ inputs.container_name }}:${{ inputs.port }}
 
     - name: Stop BuildKit (idle cleanup)
       if: ${{ inputs.cleanup == 'true' && always() }}