Define restricted Kubernetes output contract (#101)

[AntoineToussaint]

Closes #101.

Summary

• Enforce a secret-free, fail-closed promotable GitOps profile while preserving secret-bearing ephemeral local apply.
• Apply one restricted workload contract to built-in and custom controllers, including current Pod Security Standards fields, resource/probe requirements, ownership, and server admission evidence.
• Keep deployment output, configuration, environment inputs, and image digests request-scoped, and publish the complete contract through both Go and Python bindings.

Test plan

• go test ./...
• go test -race ./agents/services ./agents/testing ./resources
• uvx --from poetry==1.8.2 poetry run pytest -q codefly_cli/tests
• go vet ./agents/services ./agents/testing ./resources
• go run github.com/golangci/golangci-lint/cmd/golangci-lint@v1.64.8 run --new-from-rev=origin/main ./...
• buf lint proto --path proto/codefly/services/builder/v0/deployment.proto --path proto/codefly/services/builder/v0/docker.proto
• go mod tidy -diff
• uvx --from poetry==1.8.2 poetry check --lock
• git diff --check

Risk

This contract is intentionally fail-closed: promotable GitOps requests now return an error unless both static and requested server-side validation prove the rendered tree promotable. The repository-wide legacy lint baseline remains nonzero, but linting every line changed from origin/main is clean.