CTRL-FOUNDATION-01: add AI-led engineering controls and programme foundations

[ja573]

Summary

Establish the repository-backed engineering-control foundation for AI-assisted delivery across Thoth.

Task and evidence

• Task: CTRL-FOUNDATION-01
• Implementation report: CTRL-FOUNDATION-01-implementation-report
• Independent review brief: CTRL-FOUNDATION-01-review-brief
• Design reference index: design-references.md
• Publisher Services issue: Publisher Services: packages, distribution configuration and controlled rollout #765
• Thoth Metrics issue: Thoth Metrics: canonical ingestion, Sphinx orchestration and client cutover #766

Immutable design inputs

• Private Publisher Services design - Drive revision 3
• Private Thoth Metrics design - Drive revision 6
• Private design reference metadata

Scope

Documentation and instruction files only. This PR does not change Rust behaviour, GraphQL/export APIs, database schema or migrations, workflow behaviour, branch settings, runtime configuration, secrets, deployment or release behaviour.

Programme workflow distinction

• Publisher Services: one fresh task branch and one PR per task; no long-lived programme branch.
• Thoth Metrics: repository-local feature/metrics integration branches after branch readiness.

Decision state

ADR-0001 and ADR-0002 remain PROPOSED. Committing them does not approve dependent implementation.

Verification

At the exact review head, run the commands in the committed review brief and confirm all current-head CI is green.

The implementing conversation cannot approve or merge this PR. Final merge approval belongs to the CTO after a separate high-reasoning Codex or Claude review returns APPROVED.

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