Add local mock render worker smoke path

[RayLi-Muye]

Scope

Closes #7.

• Add a public-safe mock render worker shell script with render and postprocess modes.
• Add a local smoke test that consumes examples/mock-queue.txt, writes placeholder frame outputs, and verifies a postprocess manifest.
• Add make smoke-local and run the smoke path in GitHub Actions.
• Update README, development docs, evidence map, and delivery prompt handoff notes.

Acceptance Criteria

• Mock worker is safe to publish and contains no proprietary renderer binaries, customer scenes, license files, credentials, or cloud account details.
• Local smoke test runs without AWS credentials, a real renderer, a real queue service, object storage, Kubernetes, or cloud resources.
• CI executes the lightweight smoke path.
• Docs distinguish the mock worker from private production renderer images.

Validation

• make smoke-local
• PATH=/tmp/codex-renderfarm-tools/bin:$PATH make lint
• PATH=/tmp/codex-renderfarm-tools/bin:$PATH make template >/tmp/renderfarm-template-aws.yaml
• PATH=/tmp/codex-renderfarm-tools/bin:$PATH make template-local >/tmp/renderfarm-template-local.yaml
• PATH=/tmp/codex-renderfarm-tools/bin:$PATH scripts/render-examples.sh
• bash -n workers/mock-render-worker/mock-render-worker.sh scripts/smoke-local.sh

render-examples.sh validated default, local, and AWS GPU/SQS rendered manifests with kubeconform strict: default 3 valid resources, local 5 valid resources, AWS GPU/SQS 7 valid resources.

Docs Impact

• README adds the mock smoke path to quickstart/reviewer flow.
• Development docs list make smoke-local and describe local-only constraints.
• Evidence map adds the public mock worker smoke claim and boundary.
• Delivery prompts mark the Add mock render worker and local smoke test path #7 node as implemented and reserve future work for richer demos.

Risk / Rollback

Risk is low: this adds shell-only local tooling and a CI step, without changing Helm chart templates or production values. Rollback is removing the mock worker files, make smoke-local, the CI smoke step, and associated docs updates.

Security Notes

No AWS credentials, production resources, renderer binaries, license files, customer assets, or account-specific values are included.