Preserve Lambda ECR refs in release manifests

[gontzess]

Why

The release workflow now records lambda-arm64 image metadata for registry API ingest, but it rewrites the Lambda image ref to a short repo tag. C1 expects release metadata to carry a full or templated ECR image URI so it can resolve the account and region before Lambda deployment.

What this changes

• Preserves the full Lambda ECR image ref from GoReleaser's digest output.
• Builds the digest-pinned Lambda image URI from that same full ref.
• Updates the extractor test to assert the deployable ECR ref is retained.

Validation

• go test ./cmd/extract-images ./cmd/record-release
• go test ./...
• git diff --check