New auth-proof package, simple authentication flow

[kjartan221]

Add @bsv/auth-proof — simple, secure wallet login via signed proofs

Adds a new package under packages/middleware/auth-proof.

What it does

A small, framework- and database-agnostic library for "prove you own this key" endpoints (login, etc.). The client wallet signs a
short-lived proof of identity-key ownership; the server verifies the signature, checks freshness, and consumes the proof once.

• Signature-based — proves control of the wallet's identity key (asymmetric; the server can't forge it).
• Expiry-bound — each proof is valid for a short window (default 2 min).
• Single-use — replay protection via a store the consumer injects (consumeNonce), so the lib stays storage-agnostic.

API

const authClient = new AuthProofClient({ protocol: [2, 'myapp auth'] })
const proof = await authClient.createAuthProof(wallet, backendPublicKey, 'login')

const authServer = new AuthProofServer({ protocol: [2, 'myapp auth'] })
const result = await authServer.verifyAuthProof(serverWallet, proof, 'login', { consumeNonce })

AuthProofClient / AuthProofServer classes are thin wrappers over standalone functions (createAuthProof, verifyAuthProof, …), which are
also exported. Options (protocol, windowMs, clockSkewMs) must match on client and server.

Included

• src/ — core functions + the two classes, fully typed.
• Jest tests (13) covering serialization, freshness/expiry bounds, signature verification (including malformed-input handling), and
  single-use/replay.
• README.md + docs/usage.md with client/server examples and both Mongo-TTL and in-memory consumeNonce patterns.

[sonarqubecloud]

Quality Gate failed

Failed conditions
5.2% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud