feat(docker-build): support Docker Hub registry alongside DOCR and GHCR (#179)

.github/workflows/docker-build.yml

@@ -20,7 +20,7 @@ on:
   workflow_call:
     inputs:
       images:
-        description: "Image repositories to push, one per line (registry.digitalocean.com/... and/or ghcr.io/...)"
+        description: "Image repositories to push, one per line (registry.digitalocean.com/..., ghcr.io/... and/or docker.io/...)"
         type: string
         required: true
       platforms:
@@ -91,10 +91,10 @@ on:
         description: "DigitalOcean token or DOCR robot with write access; used when an image lives in registry.digitalocean.com"
         required: false
       DOCKERHUB_USERNAME:
-        description: "Docker Hub user for dhi.io base images; only read with dhi-login"
+        description: "Docker Hub user for dhi.io base images and docker.io pushes; only read when configured"
         required: false
       DOCKERHUB_TOKEN:
-        description: "Docker Hub token for dhi.io base images; only read with dhi-login"
+        description: "Docker Hub token for dhi.io base images and docker.io pushes; only read when configured"
 
 permissions:
   contents: read
@@ -161,6 +161,13 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Log in to Docker Hub
+        if: ${{ contains(inputs.images, 'docker.io/') }}
+        uses: docker/login-action@81c6f93d4bc991e510b342a00b419b3bb4efc5c6 # v4.7.0
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
       - name: Set up Buildx
         uses: docker/setup-buildx-action@f87e5991a6d7451dcb8d9637bfbc97413f497069 # v4.4.1
 
@@ -186,7 +193,7 @@ jobs:
             image="${image//[[:space:]]/}"
             [ -n "$image" ] || continue
             case "$image" in
-              registry.digitalocean.com/* | ghcr.io/*) ;;
+              registry.digitalocean.com/* | ghcr.io/* | docker.io/*) ;;
               *)
                 echo "error: unsupported image repository: $image" >&2
                 exit 1
@@ -273,6 +280,13 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Log in to Docker Hub
+        if: ${{ contains(inputs.images, 'docker.io/') }}
+        uses: docker/login-action@81c6f93d4bc991e510b342a00b419b3bb4efc5c6 # v4.7.0
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
       - name: Set up Buildx
         uses: docker/setup-buildx-action@f87e5991a6d7451dcb8d9637bfbc97413f497069 # v4.4.1