Create the executable invariant ledger and generate the public proof matrix

[clintecker]

Problem

Press invariants are distributed across architecture prose, verifier implementations, issue acceptance criteria, fixtures, and scars. Nothing mechanically proves that every important claim has an owner, enforcer, positive witness, negative witness, CI layer, and documented limitation.

Scope

Create quality/invariants.yaml plus a validated schema and generated public reference.

Acceptance criteria

• Define stable invariant IDs and fields for statement, risk, owner, producer, enforcer, required test layers, positive proofs, negative proofs, CI tier, and limitations.
• Validate the ledger before test collection and produce locatable schema errors.
• Fail when a critical invariant lacks an owner, enforcer, positive proof, or negative proof.
• Fail when referenced tests, fixtures, functions, or artifacts no longer exist.
• Generate docs/INVARIANTS.md from the ledger with invariant → boundary → proof → limitation traceability.
• press selftest or the docs gate detects generated-reference drift.
• Seed the ledger with all currently documented artifact, configuration, safety, design, release, and user-input-preservation invariants.

Dependencies

• Foundation harness: Establish the pytest harness and migrate press selftest into reusable tests #78
• Completes the invariant-matrix portion of Publish an architecture, invariant, and artifact-contract reference for users and contributors #33.