Generalize artifacts Lambda buildspec for mission deploys

[jamesray]

Summary

• Generalizes the artifacts Lambda CodeBuild buildspec around MISSION_NAME.
• Keeps HERMES as the default behavior while allowing mission-specific ECR repo names, base images, and requirements files.
• Passes MISSION_NAME, LAMBDA_PIPELINE=ARTIFACTS, and the image tag into the architecture build so deployments can be driven automatically again.

Why

The current buildspec is hard-coded around the original HERMES deployment path. This makes it harder to reuse the same Lambda repo for SWxSOC pipeline and future mission deployments. This change keeps the existing HERMES default while making the build/deploy handoff mission-aware.

Validation

• Parsed buildspec.yml as YAML with Ruby.
• Ran git diff --check.
• Confirmed the Dockerfile accepts BASE_IMAGE and REQUIREMENTS_FILE build args.
• Scanned the changed file for high-confidence credentials; no AWS keys, GitHub tokens, Slack tokens, or private keys found.