chore(images): migrate base images to private -stable aliases

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dliub

cmd/hasura-ndc-go/command/internal/templates/new/.hasura-connector/Dockerfile.tmpl

@@ -1,5 +1,5 @@
 # build context at repo root: docker build -f Dockerfile .
-FROM golang:1.26 AS builder
+FROM us-docker.pkg.dev/hasura-container-images/external-images/docker.io/library/golang:1.26-stable AS builder
 
 WORKDIR /app
 COPY go.mod go.sum ./

example/reference/.hasura-connector/Dockerfile

@@ -1,5 +1,5 @@
 # build context at repo root: docker build -f Dockerfile .
-FROM golang:1.22 AS builder
+FROM us-docker.pkg.dev/hasura-container-images/external-images/docker.io/library/golang:1.22-stable AS builder
 
 WORKDIR /app
 COPY . .