feat(ci/cd): Add artifact bucket and ECS deployment support

- Create S3 artifact bucket with encryption and versioning
- Add ECR lifecycle policy to maintain maximum 5 images
- Add OutputArtifacts to build stage for deployment
- Add Deploy stage with ECS provider
- Update CodePipeline artifact store to use ArtifactBucket
- Replace hardcoded bucket names with parameterized references
- Add IAM permissions for ECS task definition and service management
- Add buildspec commands to generate image definitions file

ci/buildspec.yml

@@ -16,3 +16,6 @@ phases:
       - set -e
       - docker push ${REPOSITORY_URI}:${GIT_TAG}
       - docker push ${REPOSITORY_URI}:latest
+      - printf '[{"name":"forgejo","imageUri":"%s"}]' $REPOSITORY_URI:$GIT_TAG > imagedefinitions.json
+artifacts:
+    files: imagedefinitions.json