ci: image builds pull through a mirror instead of rate-limited Docker Hub

Author: miguel-heygen

.github/workflows/ci.yml

@@ -220,6 +220,12 @@ jobs:
         with:
           lfs: true
       - uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3
+        with:
+          # Docker Hub rate-limits anonymous pulls from shared runners; pull through Google's mirror.
+          driver-opts: image=mirror.gcr.io/moby/buildkit:buildx-stable-1
+          buildkitd-config-inline: |
+            [registry."docker.io"]
+              mirrors = ["mirror.gcr.io"]
       - name: Build BeginFrame contract image
         # A hung bun install (Dockerfile.test, run 35468046055) would
         # otherwise eat the whole job timeout instead of failing at this step.

.github/workflows/fast-video-validation.yml

@@ -32,6 +32,12 @@ jobs:
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3
+        with:
+          # Docker Hub rate-limits anonymous pulls from shared runners; pull through Google's mirror.
+          driver-opts: image=mirror.gcr.io/moby/buildkit:buildx-stable-1
+          buildkitd-config-inline: |
+            [registry."docker.io"]
+              mirrors = ["mirror.gcr.io"]
 
       - name: Build test Docker image (cached)
         uses: docker/build-push-action@10e90e3645eae34f1e60eeb005ba3a3d33f178e8 # v6

.github/workflows/regression.yml

@@ -125,6 +125,12 @@ jobs:
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3
+        with:
+          # Docker Hub rate-limits anonymous pulls from shared runners; pull through Google's mirror.
+          driver-opts: image=mirror.gcr.io/moby/buildkit:buildx-stable-1
+          buildkitd-config-inline: |
+            [registry."docker.io"]
+              mirrors = ["mirror.gcr.io"]
 
       - name: Build test Docker image (cached)
         # Normal duration is ~3 min; a bun install that errors and hangs