[codex] add end-to-end delivery workstreams

[ganesh47]

What changed

This PR lands the end-to-end delivery workstream expansion for cstack.

It adds:

• GitHub planning lineage for issue-linked discover/spec/build/review/ship/deliver runs
• validation-intelligence artifacts and inspection surfaces
• post-ship summary/evidence/follow-up artifacts
• initiative graph metadata and grouped run inspection
• delivery readiness policy and deployment-evidence artifacts
• workflow capability governance visibility
• tracker/spec/docs updates, including current issue completion status
• fallback recovery when Codex exits without writing a final artifact, with coverage for build/review/validation/ship/deliver paths

Why

The repo had the umbrella workstream broken into issues #32 through #38, but the implementation was still local and unpublished. This PR publishes the completed slice set and aligns the repo-local trackers with the issue comments that now mark those workstreams implemented.

Impact

cstack now carries richer local-first artifact lineage across planning, validation, shipping, post-ship follow-up, initiative grouping, and capability policy inspection. Failure handling is also more robust when Codex exits before writing final.md.

Validation

• npm run typecheck
• npm run build
• npm test
• npm test -- --run test/codex.test.ts test/deliver.test.ts test/review.test.ts test/ship.test.ts test/validation.test.ts