feat(methods): add tenzro charge IETF I-D

[hilarl]

Add tenzro payment method (charge intent)

Summary

Adds specs/methods/tenzro/draft-tenzro-charge-00.md registering
the tenzro payment method for HTTP Payment Authentication
(I-D.httpauth-payment). The Tenzro Ledger is a multi-VM L1
(EVM + SVM + Canton/DAML over a single underlying balance via the
Sei-V2 pointer model) — the tenzro method exposes a unified
payment surface that lets a single TNZO transfer settle through any
of the four façades while keeping all signature, replay, and
delegation rules consistent.

Motivation

The existing evm method already handles "any EVM-compatible chain"
via methodDetails.chainId, so a parallel chain-specific EVM-only
method for Tenzro would duplicate it. The tenzro method is
justified by three additions over evm (or any other chain-specific
method currently registered):

1. Multi-VM façade dispatch. methodDetails.facade ∈ {native, evm, svm, canton} selects which VM façade processes
   the same logical TNZO transfer. The EVM façade alone is
   insufficient because Tenzro's recipients may hold keys in any of
   the four ecosystems and the underlying balance is shared.
2. TDIP DID binding. Credentials MAY bind a did:tenzro: DID
   that servers MUST resolve before settlement. This permits
   per-credential KYC-tier and delegation-scope enforcement that has
   no counterpart in evm/solana/stellar. Tenzro Ledger is
   built around long-lived agent identities (humans + AI agents),
   so DID binding is a first-class concern.
3. Mandatory hybrid post-quantum signing. Every credential
   carries an ML-DSA-65 (FIPS 204) signature alongside the
   classical Ed25519 / secp256k1. This is a hard requirement, not
   an option — Tenzro mandates PQ resilience pre-launch.

What's in the draft

• §1 Introduction — design rationale, façade selection, charge
  flow diagram.
• §3 Terminology — TNZO, VM Façade, wTNZO/wTNZO-SPL,
  TDIP, DelegationScope, SpendingPolicy, Hybrid PQ Signature.
• §4 Request Schema — shared fields, asset identifiers (3
  encodings), recipient identifiers (4 forms incl. DIDs),
  methodDetails.facade discriminator with full per-façade
  semantics.
• §5 Credential Schema — type="authorization" (RECOMMENDED,
  EIP-712), type="transaction", type="hash". Hybrid PQ signature
  fields are REQUIRED on all three.
• §6 Verification — 7-step rule covering signature, public key
  binding, TDIP binding, DelegationScope, SpendingPolicy, and balance.
• §7 Settlement + §8 Receipts — façade-aware receipt with
  facade field.
• §9 Error Codes — 9 Tenzro-specific entries extending RFC 9457.
• §10 Security Considerations — hybrid PQ rationale, replay,
  TDIP rotation, cross-façade replay, server-paid fee risk, façade
  privacy.
• §11 IANA Considerations — registers tenzro method and binds
  charge intent to it.
• Appendix A ABNF; Appendix B reference implementation
  pointer; Appendix C worked example.

Reference Implementation

A working Rust implementation lives at
https://github.com/tenzro/tenzro-network/tree/main/crates/tenzro-payments/src/mpp
and a TypeScript client at
https://github.com/tenzro/tenzro-network/tree/main/sdk/tenzro-ts-sdk.
Both implementations cover challenge issuance, credential
verification, hybrid PQ signing, TDIP binding, delegation enforcement,
and settlement on all four façades against a live testnet at
rpc.tenzro.network.

Tests

• The reference implementation has 75 unit tests (crates/tenzro-payments)
  covering challenge / credential / receipt round-trips for all four
  façades.
• make check and make lint pass against this PR.
• Conformance examples in §B and §C decode-and-validate against the
  reference implementation.

AI assistance disclosure

Per the project's AI disclosure norms: parts of this draft were
prepared with AI assistance from Claude Code. All technical decisions,
verification logic, and final wording were reviewed and authored by
the human author (Hilal Agil, hilal@tenzro.com). The reference
implementation was developed independently in
tenzro/tenzro-network over preceding months.

Checklist

• Filename draft-{network}-{intent}-{NN}.md with
  {network}=tenzro, {intent}=charge, {NN}=00.
• Located under specs/methods/tenzro/.
• Frontmatter follows STYLE.md (kramdown-rfc, IETF I-D format).
• Conventional Commit subject:
  feat(methods): add tenzro charge method.
• DCO sign-off.
• No mainnet-only references; all examples use testnet endpoints
  or generic placeholders.