feat: commitment-bound quote pricing (ADR-0004)

[grumbach]

ADR-0004: commitment-bound quote pricing — node side. Builds on the ADR-0002 storage-audit work (#128, merged).

Binds a quote's price to the node's audited storage commitment so a node cannot lie about how much it stores to inflate what it charges. The delivered guarantee is a price ceiling: to be paid above the empty-node baseline, a node must surrender a signed commitment that passes binding checks before payment and faces audit after it.

What

• Forced price. A quote prices from the live commitment's committed key count and pins that commitment; price is the public formula of the count by exact recomputation (never price inversion). Both quote types (single-node + merkle candidate) carry and sign the binding.
• Ship the commitment. The node sends the signed commitment alongside each quote, so any receiver verifies the binding with no extra round trip.
• Storers re-check + cross-check. Every storer re-runs the arithmetic on every quote and cross-checks each claimed count against the pinned commitment (resolved from the shipped sidecar, fresh gossip, or a capped off-hot-path GetCommitmentByPin fetch), emitting portable mismatch evidence on a contradiction.
• Deterministic first audit. Monetized commitments enter a per-peer first-audit queue (newest-per-peer, dedup on real audit, retried across the per-peer cooldown), so the latest commitment earning a peer money faces an audit soon.
• Grace removed (Amendment 1). Audit answerability is made restart-durable and challenged only in-window, so a responsive audit miss is always a confirmed failure — no UnknownCommitment/Transient grace loophole.
• No receipt bloat. Commitment sidecars are stripped before a receipt is persisted or replicated.
• The commitment wire type, its pin/verification, and the pricing formula move to ant-protocol; this crate re-exports them.

Enforcement ships behind observe-only flags for a hard cutover, per the ADR's rollout. The ADR document and implementation-slices notes are included.

Release ordering

Part of the coordinated ADR-0004 cutover — publish order evmlib 0.9.0 → ant-protocol 2.3.0 → ant-node / ant-client. evmlib's change is merged (WithAutonomi/evmlib#11) pending a 0.9.0 tag/publish; the shared layer is WithAutonomi/ant-protocol#15. This branch builds today via a committed, temporary [patch.crates-io] git-branch dep block (self-labeled strip before merge); at cutover that block is deleted and the [dependencies] pins (already evmlib 0.9.0 / ant-protocol 2.3.0) resolve from the published crates.

Companion: ant-client resolve-before-pay (the client half).