Declare plugin archive release coverage

[chubes4]

Summary

Declare the transformed WordPress plugin ZIP layout so Homeboy can validate release completeness without bypasses.

What changed

• Mapped packages/wordpress-plugin into the wp-codebox archive root for the exact generated plugin ZIP artifact.
• Added a portable executable release-package contract that builds both artifacts, validates every mapped tracked plugin runtime file, and preserves the manifest-derived CLI tarball layout.

How to test

1. Run npm run test:release-package-coverage; expect The real release package builder emits exactly one plugin ZIP and one platform-derived CLI tarball; every mapped tracked plugin runtime file exists in the ZIP..
2. Run npm run smoke -- --group package; expect Package smoke checks pass; the Docker-dependent MySQL integration is skipped when Docker is unavailable..
3. Run npm run build; expect All TypeScript packages build successfully..
4. Run git diff --check; expect The patch contains no whitespace errors..

Compatibility

Configuration and test-only change. No runtime or public API behavior, plugin extension path, ZIP layout, CLI artifact layout, or existing release output is changed. The declaration enables fail-closed validation through Homeboy #8499.

Evidence

• CI expected: contracts
• CI expected: workflow-lint
• Reviewer-resolvable source evidence: Declare transformed plugin archive coverage for releases #1829
• build: Passed
• package-smoke: Passed
• release-package-coverage: Passed

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode general coding and review subagents
• Model: openai/gpt-5.6-sol
• Used for: Added and independently reviewed the generic release package coverage declaration and executable package-layout contract; Chris reviews and owns the change.

Source relationships

• Closes Declare transformed plugin archive coverage for releases #1829