ci: pull base images from Amazon ECR Public instead of Docker Hub

Docker Hub token requests from GitHub-hosted runners are failing
(auth.docker.io timeouts / 504s, falling back to the anonymous 429 limit),
blocking release builds. Switch the Dockerfile base images and the Prisma
migration check's Postgres image to Docker's official mirrors on
public.ecr.aws/docker/library, which use the same images without depending
on Docker Hub.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: brendan-kellam

.github/actions/check-prisma-migrations/action.yml

@@ -44,7 +44,7 @@ runs:
           -e POSTGRES_USER=postgres \
           -e POSTGRES_PASSWORD=postgres \
           -e POSTGRES_DB=sourcebot \
-          -p 5432:5432 postgres:16
+          -p 5432:5432 public.ecr.aws/docker/library/postgres:16
         for i in $(seq 1 30); do
           if docker exec prisma-check-pg pg_isready -U postgres -q; then
             echo "Postgres ready."

Dockerfile

@@ -13,8 +13,8 @@ ARG NEXT_PUBLIC_SENTRY_WEBAPP_DSN
 ARG NEXT_PUBLIC_SENTRY_BACKEND_DSN
 ARG NEXT_PUBLIC_BUILD_COMMIT_SHA
 
-FROM node:24-alpine3.23 AS node-alpine
-FROM golang:1.26-alpine AS go-alpine
+FROM public.ecr.aws/docker/library/node:24-alpine3.23 AS node-alpine
+FROM public.ecr.aws/docker/library/golang:1.26-alpine AS go-alpine
 # ----------------------------------
 
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