Docker BuildKit (especially with docker-container driver) may create
OCI image manifests with attestations that AWS Lambda does not support.
Lambda requires Docker V2 Schema 2 format without multi-manifest index.
This fix ensures the build script generates Lambda-compatible images
regardless of the user's Docker/BuildKit configuration.
Fixes#206
* fix: Allow the push-to-ecr.sh script to run from anywhere instead of requiring the user to cd manually
* Add docker-compose to support running locally