Publish an architecture, invariant, and artifact-contract reference for users and contributors

[clintecker]

Problem

The most valuable design ideas live across README, ROADMAP, CLAUDE.md, comments, and agent instructions. Public users cannot easily tell what is guaranteed, generated, verified, optional, or merely planned.

Acceptance criteria

• Architecture document explains book/press/toolchain boundaries and one-truth-many-projections.
• Invariant matrix names every invariant, enforcement boundary, known-bad proof, and limitation.
• Artifact matrix lists builders, inputs, outputs, verifiers, and publication destinations.
• Configuration reference includes schemas and examples.
• Explicitly distinguish generated provenance from current verification.
• Document design-versioning and breaking-change policy.
• README leads with differentiated value and links to these references rather than agent-only docs.

[clintecker]

Audit round 3 documentation proof: docs/ARCHITECTURE.md states four laws and docs/REFERENCE.md lists outputs/prerequisites, but there is still no invariant matrix (invariant → boundary → negative proof → limitation), no complete configuration schema/examples, and the artifact table omits builders, verifiers, and publication destinations. The README leads with value well; the remaining explicit acceptance criteria are not complete.